149+ Science Fair Project Ideas for 3rd Grade 2025-26

Welcome to a big list of fun and simple science fair project ideas made just for 3rd graders. A science fair project is a way to explore a question by doing a small experiment, watching what happens, and then sharing your results.

You don’t need a lot of fancy tools—just curiosity, safety, and a little help from a grown-up.

This article gives you 150 easy-to-understand project ideas. Each idea includes the goal, the materials you need, simple steps to try, and what you will learn. The language is simple so kids can follow along.

Use these projects to practice asking good questions, solving problems, and explaining your results. Pick one you like, try it, record what happens, and make a neat poster or report to show others.

Before you start, remember:

• Always work with an adult when using scissors, heat, or chemicals.
• Keep notes of what you do and what you see (dates, times, and drawings help).
• Tests should be fair: change only one thing at a time and repeat your test a few times.
• Clean up when you finish and be safe.

Now let’s jump into 150 creative, kid-friendly science fair project ideas for 3rd grade!

Must Read: 5th Grade Science Fair Project Ideas — 150 Fun & Easy Projects for Kids!

How to use this list

1. Read several ideas and pick one that excites you.
2. Gather the materials with help from an adult.
3. Follow the simple steps and write down what happens.
4. Make a chart or draw pictures to show your results.
5. Explain what you learned and why it matters.

150 Science Fair Project Ideas for 3rd Grade 2025-26

1. Plant Growth with Light Color

• Objective: See if plants grow differently under red, blue, or white light.
• Materials: Small plants or seedlings, red and blue cellophane or LED lights, white light.
• Steps: Put plants under each color, water the same, measure growth for 2–3 weeks.
• Learn: Light color can affect plant growth.

2. Which Soil Drains Fastest?

• Objective: Compare drainage in sand, potting soil, and clay soil.
• Materials: Small containers, three soil types, water, stopwatch.
• Steps: Pour same amount of water into each and time how fast it drains.
• Learn: Different soils hold and drain water differently.

3. Bouncing Ball: Does Temperature Matter?

• Objective: Test how temperature affects a ball’s bounce.
• Materials: Rubber ball, freezer, warm water bath, ruler.
• Steps: Chill one ball, warm another, drop from same height and measure bounce.
• Learn: Temperature changes material properties.

4. Paper Towel Strength Test

• Objective: Find which brand holds the most weight when wet.
• Materials: Different paper towels, water, small cup, coins.
• Steps: Make a wet paper towel bridge, add coins until it breaks.
• Learn: Paper towels have different absorbency and strength.

5. How Fast Do Ice Cubes Melt?

• Objective: Compare melting speed in sun, shade, and warm water.
• Materials: Ice cubes, bowls, timer, thermometer.
• Steps: Put equal ice cubes in each location and time melting.
• Learn: Heat sources change melting rates.

6. Homemade Volcano (Baking Soda + Vinegar)

• Objective: Observe a chemical reaction that makes fizz and foam.
• Materials: Baking soda, vinegar, dish soap, clay or paper cup.
• Steps: Build a small volcano, add baking soda and vinegar to watch eruption.
• Learn: Acid–base reactions release gas and cause bubbling.

7. Salt Water Density—Will it Float?

• Objective: See how saltwater affects floating objects.
• Materials: Clear jar, water, salt, small objects (egg, grape).
• Steps: Dissolve salt in water, place objects and compare floating to fresh water.
• Learn: Salt increases water density and helps things float.

8. Make a Simple Electric Circuit

• Objective: Light up a bulb using a battery and wires.
• Materials: Battery, small bulb, wires, tape.
• Steps: Connect battery to bulb with wires and complete the circuit.
• Learn: Electricity flows in a closed loop.

9. Magnet Strength Test

• Objective: Compare which magnet picks up more paperclips.
• Materials: Different magnets, paperclips, ruler.
• Steps: See how many paperclips each magnet can lift and how far they attract.
• Learn: Magnets have different strengths.

10. Floating Egg vs. Sinking Egg

• Objective: Test when an egg floats in saltwater.
• Materials: Egg, water, salt, tall glass.
• Steps: Add salt gradually to water and watch when egg floats.
• Learn: Density changes with dissolved salt.

11. Growing Crystals (Salt or Sugar)

• Objective: Grow crystals from a saturated solution.
• Materials: Salt or sugar, hot water, jar, string, pencil.
• Steps: Dissolve lots of salt/sugar in hot water, hang string and watch crystals form.
• Learn: Crystals form when a solution cools and becomes saturated.

12. Which Material Keeps Water Hot Longest?

• Objective: Test insulation power of cloth, foil, and plastic.
• Materials: Small cups, thermometer, hot water, different covers.
• Steps: Pour hot water into cups, cover with different materials, measure temperature over time.
• Learn: Some materials insulate heat better.

13. Rainbow with a Glass of Water

• Objective: Make a rainbow using sunlight and water refraction.
• Materials: Clear glass of water, white paper, sunlight.
• Steps: Place glass on paper in sun until a rainbow appears.
• Learn: Water bends light into colors.

14. Build a Lemon Battery

• Objective: Make a tiny battery using lemons.
• Materials: Lemons, copper and zinc (pennies and nails), wires, small LED.
• Steps: Insert metals into lemon, connect in a chain to power LED.
• Learn: Acidic juice conducts electricity.

15. Which Fruit Makes the Most Juice?

• Objective: Compare juice amounts from apples, oranges, and grapes.
• Materials: Fruit, juicer or mortar, measuring cup.
• Steps: Extract juice from equal fruit amounts and measure volume.
• Learn: Fruits have different water content.

16. Melting Race: Chocolate vs. Butter

• Objective: See which melts faster at room temperature.
• Materials: Same-sized pieces of chocolate and butter, plate, timer.
• Steps: Place both on a plate and watch which melts first.
• Learn: Different foods melt at different temperatures.

17. Water Surface Tension: Pepper and Soap

• Objective: Show how soap breaks surface tension.
• Materials: Bowl of water, ground pepper, dish soap, cotton swab.
• Steps: Sprinkle pepper, touch center with soap on swab, watch pepper move.
• Learn: Soap lowers surface tension causing movement.

18. Plant Food vs. No Plant Food

• Objective: Test fertilizer effects on plant growth.
• Materials: Two identical plants, fertilizer, water, measuring tape.
• Steps: Feed one plant fertilizer as instructed, leave the other plain, measure growth.
• Learn: Nutrients help plants grow.

19. Paper Airplane Distance Comparison

• Objective: Test which design flies farthest.
• Materials: Paper, tape, measuring tape, open area.
• Steps: Fold different airplane designs, throw each three times, average distance.
• Learn: Shape affects flight distance.

20. Make Sound with a Straw

• Objective: Create different notes by changing straw length.
• Materials: Plastic straw, scissors, ruler.
• Steps: Cut straw into different lengths, blow and compare sounds.
• Learn: Length affects pitch.

21. How Does Temperature Affect Yeast?

• Objective: Watch yeast bubble in warm vs. cold water.
• Materials: Yeast, sugar, warm and cold water, balloons, bottles.
• Steps: Mix yeast and sugar in warm and cold water in bottles, place balloon on top and watch inflate.
• Learn: Yeast is more active in warm temperatures.

22. Sink or Float: Mystery Objects

• Objective: Predict and test which items sink or float.
• Materials: Large tub of water, mixed small objects.
• Steps: Predict then test each item, record results.
• Learn: Buoyancy depends on density and shape.

23. Build a Simple Sundial

• Objective: Use a stick to track sun and tell time.
• Materials: Paper plate, stick, marker, sunny day.
• Steps: Place stick in plate, mark shadow positions each hour.
• Learn: Sun position changes during the day.

24. How Do Different Liquids Affect Rusting?

• Objective: See which liquid causes metal to rust fastest.
• Materials: Steel nails, water, saltwater, vinegar, oil, jars.
• Steps: Put nails in different liquids and observe over days.
• Learn: Some liquids speed up rust.

25. Homemade Barometer for Weather

• Objective: Make a tool to show air pressure changes.
• Materials: Jar, balloon, straw, tape, index card.
• Steps: Stretch balloon over jar, tape straw on top, mark straw position each day.
• Learn: Air pressure changes with weather.

26. Does Color Affect Heat Absorption?

• Objective: Test if dark colors get hotter than light colors.
• Materials: Black and white paper, thermometer, sunlight.
• Steps: Place papers in the sun, measure temperature after a set time.
• Learn: Dark colors absorb more heat.

27. Simple Water Filter

• Objective: Build a filter using sand and gravel and test dirt removal.
• Materials: Plastic bottle, sand, gravel, coffee filter, dirty water.
• Steps: Layer gravel and sand inside bottle, pour dirty water and collect filtered water.
• Learn: Filters remove particles but not all germs.

28. How Strong is a Paper Bridge?

• Objective: Test how much weight folded paper can hold.
• Materials: Paper, books, small weights or coins.
• Steps: Fold paper into bridge shapes, place between supports, add weight until it breaks.
• Learn: Shape and folds add strength.

29. Shadow Length Throughout the Day

• Objective: Measure how a shadow changes from morning to afternoon.
• Materials: Toy or stick, ruler, notebook, sunny day.
• Steps: Measure the shadow every hour and record.
• Learn: Shadow tells sun angle changes.

30. Dancing Raisins in Soda

• Objective: See how bubbles make raisins move up and down.
• Materials: Clear soda, raisins, glass.
• Steps: Drop raisins in soda and watch them rise and fall.
• Learn: Gas bubbles stick to rough surfaces and lift them.

31. Homemade Compass

• Objective: Make a simple compass with a needle and magnet.
• Materials: Sewing needle, magnet, cork, bowl of water.
• Steps: Magnetize needle, place on cork in water and watch it point north.
• Learn: Earth has a magnetic field.

32. Comparing Tooth Decay with Candy

• Objective: Test how soda vs. water affects eggshells (like teeth).
• Materials: Eggs, soda, water, jar, days of observation.
• Steps: Submerge eggs in soda and water, observe shell changes after days.
• Learn: Sugary drinks harm teeth.

33. Capillary Action in Plants

• Objective: See how colored water travels up a stem.
• Materials: White flowers or celery, food coloring, water, jars.
• Steps: Put colored water with flower and watch color move into petals.
• Learn: Plants move water up through tiny tubes.

34. How Fast Do Seeds Germinate?

• Objective: Test seed germination in light vs. dark.
• Materials: Seeds (bean), paper towel, zip bag, light and dark spots.
• Steps: Put seeds in moist towel in bag, place in light or dark and check sprouting days.
• Learn: Light can affect seed sprouting.

35. Balloon Rocket Race

• Objective: Learn about thrust using balloon rockets.
• Materials: Balloon, string, straw, tape.
• Steps: Thread string, attach inflated balloon to straw with tape, release and race.
• Learn: Air leaving the balloon makes it move forward.

36. Invisible Ink with Lemon Juice

• Objective: Write secret messages that appear when heated.
• Materials: Lemon juice, paper, cotton swab, lamp or iron (adult help).
• Steps: Write with lemon juice, let dry, carefully heat to reveal message.
• Learn: Heat causes chemical changes making writing visible.

37. Which Liquid Makes Colors Run?

• Objective: Test how water, vinegar, and rubbing alcohol affect markers.
• Materials: Coffee filter, markers, water, vinegar, alcohol, cups.
• Steps: Draw on filter, dip edge into each liquid and watch color spread.
• Learn: Different liquids dissolve ink differently.

38. How Do Ants Find Food?

• Objective: Observe ant trails and how they follow scent.
• Materials: Sugar or crumbs, paper, magnifying glass, outdoor area.
• Steps: Place food and watch ants create trails, take notes.
• Learn: Ants use scent trails to communicate.

39. Floating Paper Clip on Water

• Objective: See how surface tension lets a paperclip float.
• Materials: Bowl of water, paperclip, tissue paper, steady hand.
• Steps: Lay tissue on water, set paperclip on tissue, then gently remove tissue.
• Learn: Surface tension can hold lightweight metal.

40. Make a Simple Parachute

• Objective: Test how size of parachute affects falling speed.
• Materials: Plastic bag, string, small toy.
• Steps: Make parachutes of different sizes and drop from height, time descent.
• Learn: Larger parachutes slow fall more.

41. Compare Sugar vs. Artificial Sweetener

• Objective: See if both dissolve equally in cold water.
• Materials: Sugar, sweetener, cold water, spoons, jars.
• Steps: Stir equal amounts into cold water and watch how they dissolve.
• Learn: Different sweeteners dissolve differently.

42. Which Paper Absorbs the Most Water?

• Objective: Test napkin, tissue, and paper towel absorbency.
• Materials: Different papers, water, measuring cup.
• Steps: Drop same water amount on each and see which soaks it up.
• Learn: Materials have different absorbency.

43. How Strong is a Magnet Through Paper?

• Objective: See how many layers of paper stop magnet power.
• Materials: Magnet, paper sheets, paperclips.
• Steps: Put layers of paper between magnet and paperclips and count.
• Learn: Magnet strength weakens with distance.

44. Make a Lava Lamp

• Objective: Create bubbling oil-and-water lamp with color and fizz.
• Materials: Clear bottle, water, oil, food coloring, Alka-Seltzer tablet.
• Steps: Mix water and oil, add color, drop tablet and watch blobs move.
• Learn: Oil and water don’t mix; gas moves blobs.

45. Testing Elastic Band Strength

• Objective: Compare stretchiness of rubber bands by measuring stretch length.
• Materials: Rubber bands, ruler, weights.
• Steps: Hook weight on band, measure stretch, compare types.
• Learn: Different rubber bands have different elasticity.

46. How Plants Breathe—Stomata Observation

• Objective: See tiny stomata on leaves (adult help for microscope).
• Materials: Leaf, clear nail polish, tape, microscope or magnifier.
• Steps: Make a peel with nail polish, view under magnifier to find stomata.
• Learn: Leaves have tiny openings for gas exchange.

47. Which Liquid Cleans Pennies Best?

• Objective: Compare cleaning power of ketchup, vinegar, and soap.
• Materials: Tarnished pennies, ketchup, vinegar, soap, toothbrush.
• Steps: Clean pennies with each liquid and compare shine.
• Learn: Acids remove tarnish.

48. Does Music Affect Plant Growth?

• Objective: Play music to one plant and silence another to compare growth.
• Materials: Two plants, music player, speaker.
• Steps: Play music for one plant daily, keep other quiet, measure growth after weeks.
• Learn: Sound may influence plant growth (observe carefully).

49. Simple Weather Station—Rain Gauge

• Objective: Measure rainfall amount over a week.
• Materials: Clear jar, ruler, marker.
• Steps: Put jar outside, mark water level after each rain.
• Learn: How much rain falls in your area.

50. How Do Different Surfaces Affect Slipping?

• Objective: Test friction on wood, tile, and carpet using a toy car.
• Materials: Toy car, ramp, different surface strips, ruler.
• Steps: Roll car down ramp onto each surface and measure distance traveled.
• Learn: Surface type affects friction and stopping distance.

51. How Fast Does Bread Mold Grow?

• Objective: See mold growth on plain vs. buttery bread.
• Materials: Slices of bread, plastic bags, water, peanut butter (optional).
• Steps: Slightly wet each slice, put in bags, store in dark and watch for mold.
• Learn: Moisture and food type affect mold growth.

52. Balloon and Static Electricity

• Objective: Create static to pick up paper pieces with a balloon.
• Materials: Balloon, small paper bits, sweater.
• Steps: Rub balloon on sweater and bring near paper bits to lift them.
• Learn: Static electricity attracts small objects.

53. Which Fruit Attracts Fruit Flies Most?

• Objective: Compare attractiveness of banana, apple, and orange.
• Materials: Fruit pieces, jars, paper cone trap.
• Steps: Place fruit in jars with cone lid and count flies after a day.
• Learn: Ripeness and scent attract insects.

54. Testing pH with Red Cabbage

• Objective: Make a natural pH indicator from cabbage juice.
• Materials: Red cabbage, blender, water, clear cups, vinegar, baking soda.
• Steps: Make cabbage juice, add to cups with different liquids, watch color change.
• Learn: Acids and bases change indicator color.

55. Which Shape Makes the Strongest Egg Shell?

• Objective: Test pressure resistance of egg shapes (adult help).
• Materials: Eggs, books, small weights.
• Steps: Put eggs upright and add weight gradually until they crack.
• Learn: Curved shapes distribute pressure.

56. How Do Different Fabrics Dry?

• Objective: Compare drying time of cotton, polyester, and wool.
• Materials: Small fabric swatches, water, hanger, timer.
• Steps: Wet each swatch equally, hang them and time drying.
• Learn: Fabric type affects drying speed.

57. Simple Pendulum—Length vs. Swing Time

• Objective: See how pendulum string length changes swing speed.
• Materials: String, small weight, stopwatch.
• Steps: Make pendulums of different lengths and time swings.
• Learn: Longer pendulums swing slower.

58. How Do Seeds Travel?

• Objective: Compare how wind, water, and animals might spread seeds.
• Materials: Different seeds (dandelion, acorn), fan, water cup.
• Steps: Blow seeds with fan, place near water, observe behavior.
• Learn: Seeds have special features for travel.

59. Build a Water Wheel

• Objective: Convert flowing water into wheel motion.
• Materials: Plastic wheel or bottle, spoons, water source, basin.
• Steps: Attach spoons to a wheel, pour water to turn the wheel and count rotations.
• Learn: Flowing water can do work.

60. Test Which Bread Rises Best

• Objective: Compare yeast bread with and without sugar.
• Materials: Flour, yeast, water, sugar, bowls, measuring.
• Steps: Make two doughs, add sugar to one, watch rising time and height.
• Learn: Sugar feeds yeast and affects rise.

61. Does Shape Affect How Ice Melts?

• Objective: Test melting times for cube vs. sphere of same ice volume.
• Materials: Ice molds (cube and ball), tray, timer.
• Steps: Make same-volume ice shapes and time melting at room temperature.
• Learn: Shape affects surface area and melting rate.

62. Homemade Thermometer with Straw

• Objective: Make a simple liquid thermometer using colored water.
• Materials: Clear bottle, colored water, straw, clay.
• Steps: Seal straw in bottle with clay so water rises in straw when heated.
• Learn: Liquid expands with heat.

63. Which Apples Brown Fastest?

• Objective: Test browning speed in lemon juice, water, and air.
• Materials: Apple slices, lemon juice, water, plates.
• Steps: Coat slices differently and watch browning.
• Learn: Acid prevents browning.

64. Make a Weather Vane

• Objective: Build a tool to show wind direction.
• Materials: Straw, paper, pencil with eraser, pin.
• Steps: Make arrow on straw, balance on pin and see which way it points.
• Learn: Wind direction can be measured.

65. Compare Bouncing of Different Balls

• Objective: Test bouncy ball, tennis ball, and basketball from same height.
• Materials: Several ball types, ruler, measuring tape.
• Steps: Drop from fixed height and measure bounce height.
• Learn: Material affects bounce.

66. How Do Sugary Drinks Affect Plants?

• Objective: Water plants with soda, juice, and water and watch growth.
• Materials: Three plants, soda, juice, water, measuring tape.
• Steps: Water each plant with different liquid and measure health over time.
• Learn: Sugary drinks harm plant health.

67. How Does Salt Affect Plant Seeds?

• Objective: Test seed germination in salty vs. fresh water.
• Materials: Seeds, salt water, fresh water, paper towels.
• Steps: Place seeds in moist towels with different water and watch sprouting.
• Learn: Salt can prevent seeds from sprouting.

68. Float a Penny with Surface Tension

• Objective: Place a penny gently and see if water surface can hold it.
• Materials: Penny, bowl of water, steady hand.
• Steps: Slowly lower penny to water surface and observe.
• Learn: Surface tension can support denser objects briefly.

69. Seed Sorting by Density

• Objective: See if healthy seeds sink and bad seeds float.
• Materials: Seeds, water, bowl.
• Steps: Put seeds in water and sort sinking vs. floating seeds and test germination.
• Learn: Density can indicate seed quality.

70. Make a Simple Hydrometer

• Objective: Test liquid density using floating objects.
• Materials: Straw, clay, water, salt.
• Steps: Seal one end of straw with clay, float in liquids and mark level.
• Learn: Denser liquids make objects float higher.

71. Color Mixing with Skittles

• Objective: Watch candy colors dissolve and spread in water.
• Materials: Skittles, plate, warm water.
• Steps: Arrange candies and add tiny water to see colors spread.
• Learn: Sugar shells dissolve and color diffuses.

72. Which Cleaner Removes Stains Best?

• Objective: Test different cleaners on crayon or juice stains.
• Materials: Fabric samples, marker or juice stains, soap, stain remover.
• Steps: Treat stained spots with different cleaners and compare results.
• Learn: Some cleaners remove stains better.

73. Simple Airplane Wing Lift

• Objective: Test lift with different wing shapes using paper gliders.
• Materials: Paper, scissors, measuring tape.
• Steps: Make gliders with wide vs. narrow wings and measure glide distance.
• Learn: Wing shape affects lift and distance.

74. Does Water Hardness Affect Soap Bubbles?

• Objective: Compare bubble making with hard vs. soft water.
• Materials: Water samples (tap and distilled), dish soap, bubble wand.
• Steps: Mix soap with each water type and blow bubbles, count size or longevity.
• Learn: Minerals in water affect bubble quality.

75. How Fast Do Different Candles Burn?

• Objective: Test burn time for tall vs. short candles (adult supervision).
• Materials: Different candles, stopwatch, heatproof surface.
• Steps: Light candles and time until a set point, measure wax used.
• Learn: Size and wax type change burn rate.

76. How Do Different Shoes Grip?

• Objective: Test which shoe sole slides least on a ramp.
• Materials: Small ramp, samples of different shoe soles or materials, toy car base.
• Steps: Place different soles on ramp and measure sliding distance.
• Learn: Sole material affects grip.

77. Testing How Fog Forms

• Objective: Make fog in a jar using warm water and ice.
• Materials: Jar, hot water, ice, metal plate.
• Steps: Pour hot water in jar and place ice on top to condense fog.
• Learn: Cold condenses water vapor into fog.

78. How Do Seeds Respond to Light Direction?

• Objective: See if seedlings bend toward light.
• Materials: Seedlings in box with one light hole, soil, water.
• Steps: Place light only on one side and watch seedling growth direction.
• Learn: Plants grow toward light (phototropism).

79. Which Surface Makes the Most Static?

• Objective: Rub balloon on different fabrics to see static cling.
• Materials: Balloon, wool, cotton, silk, small paper bits.
• Steps: Rub and test pickup of paper bits.
• Learn: Different materials create static differently.

80. Make Oobleck—Is It Solid or Liquid?

• Objective: Explore non-Newtonian fluids using cornstarch and water.
• Materials: Cornstarch, water, bowl.
• Steps: Mix until thick, punch to see solid-like, let it flow like liquid.
• Learn: Some mixtures change behavior under force.

81. Test Which Foods Mold First

• Objective: Compare mold on bread, fruit, and cheese.
• Materials: Food samples, plastic bags, observation journal.
• Steps: Store equal samples and watch mold growth over days.
• Learn: Different foods mold at different rates.

82. Which Brand of Glue Holds Best?

• Objective: Compare tack strength of school glue, glue stick, and hot glue.
• Materials: Paper strips, glue types, small weights.
• Steps: Glue paper strips together with each glue and add weight until they separate.
• Learn: Adhesives have different strengths.

83. **Does Water Temperature Affect Dissolving?

• Objective: Test how temperature changes how fast salt dissolves.
• Materials: Salt, cold and hot water, spoons, timer.
• Steps: Stir same salt amount in different temperatures and time dissolving.
• Learn: Heat speeds dissolving.

84. Make a Simple Seismograph

• Objective: Show vibrations by drawing with a hanging marker.
• Materials: Box, string, marker, paper, toy that shakes table.
• Steps: Suspend marker above paper and create small vibrations to record lines.
• Learn: Vibrations can be recorded visually.

85. How Do Different Liquids Evaporate?

• Objective: Compare evaporation of water, alcohol, and oil.
• Materials: Small shallow dishes, equal liquid amounts, scale or visual marks.
• Steps: Leave dishes and observe liquid loss over time.
• Learn: Volatility affects evaporation.

86. Soundproofing with Materials

• Objective: Test which material blocks sound best.
• Materials: Boxes, blankets, foam, phone playing sound, decibel app (adult help).
• Steps: Put sound source in box covered with different materials and compare loudness.
• Learn: Some materials absorb sound better.

87. How Do Flowers Open?

• Objective: Watch a closed bud open over time (use a time-lapse if possible).
• Materials: Buds, camera or notebook, sunlight.
• Steps: Watch and note changes every hour.
• Learn: Flower opening follows internal rhythms and light.

88. Which Coins Conduct Electricity?

• Objective: Test conductance of different coins and metals.
• Materials: Battery, wires, small bulb, coins.
• Steps: Include coin in circuit and see if bulb lights.
• Learn: Metals conduct electricity differently.

89. Plant Leaf Color Change with Temperature

• Objective: See if cool nights affect leaf color faster.
• Materials: Potted plant, cool and warm spot choices.
• Steps: Move plant to cooler spot at night and observe leaf color over weeks.
• Learn: Temperature influences plant pigments.

90. How Do Different Liquids Affect Candle Flame?

• Objective: Test how oil or water near a candle changes flame (adult supervision).
• Materials: Candle, small dish of water, small oil dish, adult present.
• Steps: Place dishes near candle and watch flame behavior safely.
• Learn: Surrounding air and vapors affect flames.

91. Make a Model of the Water Cycle

• Objective: Create a small closed system showing evaporation and condensation.
• Materials: Clear container, water, plastic wrap, small rock.
• Steps: Place water in container, cover with wrap, put in sun and watch condensation.
• Learn: Water evaporates and becomes clouds then returns as rain.

92. Compare How Much Gas Different Foods Produce

• Objective: Use yeast and sugar mixtures to see gas from different food types.
• Materials: Yeast, different sugars (table sugar, honey), bottles, balloons.
• Steps: Mix each food with yeast and watch balloon inflate differently.
• Learn: Types of sugar feed yeast differently.

93. Testing How Plants Respond to Touch

• Objective: See if gentle touching affects plant growth like mimosa (sensitive plant).
• Materials: Sensitive plant (if available), stick, notebook.
• Steps: Touch some plants daily and leave others alone to compare.
• Learn: Some plants have responses to touch.

94. Which Spices Dissolve Fastest?

• Objective: Compare dissolution of salt, pepper, and cinnamon in water.
• Materials: Small jars, measured spices, water, stirrers.
• Steps: Stir each spice in water and observe whether it dissolves or floats.
• Learn: Solubility differs among substances.

95. Does Shape of Ice Cube Affect Coffee Cooling?

• Objective: Test cooling speed with different ice shapes.
• Materials: Coffee or warm water, cube and crushed ice, thermometer.
• Steps: Add same ice volume and measure temperature drop over time.
• Learn: Surface area changes cooling rate.

96. How Does Altitude Affect Boiling Point?

• Objective: See if water boils at different temperatures (use safe demonstration or research).
• Materials: Kettle, thermometer (adult supervision), or explain with chart.
• Steps: Measure boiling in different places or explain effect using simple diagram.
• Learn: Lower pressure at high altitude lowers boiling point.

97. Which Fruit Has the Most Vitamin C? (Simple Test)

• Objective: Compare citrus fruits using store info or an indicator test (supervised).
• Materials: Oranges, lemons, neutral indicator (or use nutrition facts).
• Steps: Test or look up vitamin C content, compare.
• Learn: Fruits vary in vitamin C content.

98. How Does Bubble Solution Change with Soap Type?

• Objective: Test bubble size and longevity with different soaps.
• Materials: Dish soap brands, water, glycerin (optional), bubble wand.
• Steps: Mix and blow bubbles, time how long they last.
• Learn: Ingredients affect bubbles.

99. Growing Mold in Different Temperatures

• Objective: Test mold growth at warm vs. cool places.
• Materials: Bread slices, plastic bags, warm and cool locations.
• Steps: Store slices in different temps and observe mold.
• Learn: Temperature affects mold growth speed.

100. Solar Oven Smores

• Objective: Use sunlight to melt chocolate and marshmallows in a small solar oven.
• Materials: Pizza box, foil, plastic wrap, black paper, marshmallows, chocolate, graham crackers.
• Steps: Make solar oven with foil, place s’mores inside and position in sun until melted.
• Learn: Sunlight can be used as heat energy.

101. How Does Color Affect Bee Visits?

• Objective: Observe whether bees visit certain flower colors more (outdoor and safe).
• Materials: Potted flowers of different colors, notebook, outdoor spot.
• Steps: Count bee visits to each color during set times.
• Learn: Pollinators may prefer some colors.

102. Which Snack Keeps Your Teeth Healthier?

• Objective: Use egg shells as tooth models to test snack effects.
• Materials: Eggshells, milk, soda, water, sugar, jars.
• Steps: Soak shells in different liquids and observe changes.
• Learn: Some snacks and drinks damage teeth more.

103. How Do Trees Help Cool the Air?

• Objective: Measure temperature under a tree and in the sun.
• Materials: Thermometer, sunny day, shady tree.
• Steps: Record temperature in shade and sun and compare.
• Learn: Plants and shade lower temperatures.

104. Make a Simple Kaleidoscope

• Objective: Build a kaleidoscope and explore light reflection.
• Materials: Cardboard tube, small mirrors or mirrored paper, beads, tape.
• Steps: Place mirrors inside tube at angles and add beads at end, look through to see patterns.
• Learn: Multiple reflections create symmetric patterns.

105. Which Balloons Fly Farther: Filled with Air or Helium?

• Objective: Compare floating and movement of air-filled vs helium-filled balloons (adult help).
• Materials: Balloons, helium tank (adult), air pump.
• Steps: Release each (tied to weight if needed) and observe.
• Learn: Lighter-than-air gases cause lift.

106. Which Household Item Cleans Penny Best?

• Objective: Test lemon, toothpaste, and baking soda for cleaning pennies.
• Materials: Pennies, cleaners, toothbrush, water.
• Steps: Clean pennies and compare shine.
• Learn: Different cleaners work differently.

107. How Does Temperature Affect Bread Rising?

• Objective: Test yeast in warm vs. cool places for bread rise.
• Materials: Bread dough, two different temperature spots, measuring.
• Steps: Place dough in warm and cool places and compare volume after time.
• Learn: Warmth speeds yeast activity.

108. Paper Chromatography with Markers

• Objective: Separate ink colors using chromatography.
• Materials: Coffee filter, markers, water, cup.
• Steps: Draw dot, suspend filter edge in water and watch colors spread.
• Learn: Marker ink is a mix of colors.

109. Which Type of Water Makes a Plant Grow Best?

• Objective: Test tap, rain, and bottled water on plant growth.
• Materials: Three plants, different water sources, ruler.
• Steps: Water each plant with a different type and record growth.
• Learn: Water quality can affect plants.

110. How Strong is a Honeycomb Structure?

• Objective: Build honeycomb shapes from cardboard and test weight support.
• Materials: Cardboard strips, tape, small weights.
• Steps: Make hexagon honeycombs and add weight to test strength.
• Learn: Hexagons are strong shapes in nature.

111. Make a Simple Stethoscope

• Objective: Hear heartbeats and compare rest vs. after exercise.
• Materials: Funnel, tubing, tape, volunteer (adult).
• Steps: Assemble and listen to heart before and after jumping jacks.
• Learn: Heart rate changes with activity.

112. Which Color Ice Melts Fastest?

• Objective: Test whether dark-colored ice melts faster in sun.
• Materials: Colored ice cubes, tray, sunny spot.
• Steps: Place colored ice in sun and time melting.
• Learn: Dark colors absorb more heat.

113. How Do Different Pencils Make Darker Lines?

• Objective: Compare graphite hardness for darkness.
• Materials: Pencils (HB, 2B, etc.), paper.
• Steps: Draw lines and compare darkness with visual scale.
• Learn: Pencil grade affects darkness.

114. Which Material Makes the Best Insulator for a Cup?

• Objective: Test how long drinks stay hot in paper, foam, and ceramic cups.
• Materials: Cups of different materials, hot water, thermometer.
• Steps: Measure temperature over time for each cup.
• Learn: Some materials keep heat better.

115. How Do Antacid Tablets React in Water?

• Objective: Observe fizzing rates of brands of antacid (adult).
• Materials: Different antacid tablets, water, jars.
• Steps: Drop tablets and time fizzing and bubble amount.
• Learn: Chemical composition affects reaction speed.

116. Does Salt Melt Ice Faster?

• Objective: Test salt vs. sugar on melting ice.
• Materials: Ice cubes, salt, sugar, timer.
• Steps: Sprinkle on ice and measure how fast they melt.
• Learn: Salt lowers freezing point causing faster melt.

117. How Does Volume Affect Popping Popcorn?

• Objective: Count popped kernels from different bag sizes or pot volumes.
• Materials: Popcorn kernels, pot or microwave, measuring cup.
• Steps: Pop same amount and count unpopped kernels.
• Learn: Heat distribution affects popping.

118. Test Which Sponges Absorb Most Water

• Objective: Compare kitchen sponge, dishcloth, and towel absorbency.
• Materials: Different sponge types, measured water, scale or measuring cup.
• Steps: Soak equally and squeeze into cup to measure water held.
• Learn: Materials differ in absorption capacity.

119. Which Writing Tool Dries Fastest?

• Objective: Time drying of ink from pen, marker, and pencil.
• Materials: Paper, pen, marker, pencil, stopwatch.
• Steps: Write same mark and touch after intervals to test dry feel.
• Learn: Ink formulas dry at different speeds.

120. Test Which Color Attracts Butterflies

• Objective: Count butterfly visits to colored paper with sugar water.
• Materials: Colored paper, sugar water, outdoor area.
• Steps: Place sugar water on different colors and count visits.
• Learn: Butterflies may prefer certain colors.

121. How Tight Does a Lid Need to Be to Keep Water In?

• Objective: Test leaks on different jar lids and seals.
• Materials: Jars, lids, water, tilt test.
• Steps: Fill jars, close lids with different tightness, tilt and check leaks.
• Learn: Seal tightness affects leakage.

122. Which Fabrics Fade Fastest in Sun?

• Objective: Place fabric swatches in sun and shade and compare fading.
• Materials: Fabric swatches, sunny spot, notebook.
• Steps: Leave for days and compare color change.
• Learn: Sunlight fades dyes over time.

123. Make a Simple Telegraph

• Objective: Send messages using on/off clicks and learn Morse code basics.
• Materials: Battery, buzzer, switch (or paper cup and string for signal), wires.
• Steps: Connect circuit to make sound when closed and create simple code.
• Learn: Early communication used simple electrical signals.

124. How Do Plant Leaves React to Salt Water?

• Objective: Spray leaves with salt water vs. fresh and observe.
• Materials: Two similar plants, salt water, spray bottle.
• Steps: Spray one plant with salt solution, the other with fresh water and watch changes.
• Learn: Salt can damage leaf tissue.

125. Which Type of Sugar Burns Faster?

• Objective: Test burning sugar granules vs. cubes (adult supervision).
• Materials: Table sugar, sugar cubes, heat source, safety gear.
• Steps: Carefully heat small amounts and observe burning behavior.
• Learn: Surface area influences combustion (adult demo only).

126. How Loud Are Different Musical Instruments?

• Objective: Measure loudness of recorder, drum, and tambourine (use relative measures).
• Materials: Instruments, quiet room, phone sound meter app (adult help).
• Steps: Play each instrument and compare readings or judge by ear.
• Learn: Instruments produce different sound levels.

127. Build a Mini Greenhouse

• Objective: See how warmth and humidity in a mini greenhouse affect plant growth.
• Materials: Clear plastic container, soil, seed, sunlight.
• Steps: Plant seed in container, close lid and compare to open pot.
• Learn: Greenhouses trap heat and moisture for plant growth.

128. How Do Smooth vs. Rough Surfaces Affect Rolling?

• Objective: Roll a marble across sandpaper, tile, and cloth and compare distance.
• Materials: Marble, ramps, different surface samples.
• Steps: Roll marble and measure travel distance.
• Learn: Surface texture changes friction.

129. Which Paper Boat Holds Most Weight?

• Objective: Fold different boat styles and test floating weight.
• Materials: Paper, small weights or coins, basin of water.
• Steps: Float boats and add coins until sinking.
• Learn: Design affects buoyancy and balance.

130. Does Soap Affect Plant Growth?

• Objective: Test mild soap water on leaves vs. plain water (small amounts).
• Materials: Two plants, very diluted soap water, water.
• Steps: Spray one plant lightly, leave other plain, observe over weeks.
• Learn: High soap can harm plants; tiny amounts used for pests can have effects.

131. Which Color Crayon Melts Fastest?

• Objective: Test melting times for crayons of different colors under heat lamp (adult supervision).
• Materials: Crayons, lamp, plate, timer.
• Steps: Place crayons under lamp and time melting.
• Learn: Color and dye may slightly affect heat absorption.

132. Test How Many Paper Cups a Straw Holds

• Objective: Stack cups using a straw and see how many can be supported (engineering challenge).
• Materials: Straws, paper cups, tape.
• Steps: Build vertical structure using straw support and see how many cups stack before collapse.
• Learn: Simple engineering and balance.

133. How Does Wind Speed Move Objects?

• Objective: Use different fan speeds to move lightweight objects and measure distance.
• Materials: Fan with speeds, paper, feathers, small balls.
• Steps: Turn fan to different settings and measure how far items move.
• Learn: Wind power pushes objects differently by size and shape.

134. Make a Homemade Barometer with Balloon and Straw

• Objective: Track air pressure by noting straw movement over days.
• Materials: Jar, balloon, straw, tape, card with scale.
• Steps: Cover jar with balloon, fix straw and mark position daily.
• Learn: Barometers show pressure changes that relate to weather.

135. Do Plants Prefer Plain or Colored Light?

• Objective: Grow plants under colored film and compare leaf color and growth.
• Materials: Small plants, colored cellophane, light source.
• Steps: Cover lights with different colors and grow plants, measuring growth.
• Learn: Light color affects plant development.

136. How Does a Thermos Keep Drinks Hot?

• Objective: Test temperature over time in thermos vs. open cup.
• Materials: Thermos, cup, hot water, thermometer.
• Steps: Fill both and measure temperature every 10 minutes.
• Learn: Vacuum layers prevent heat loss.

137. Testing Which Fruit Attracts Birds

• Objective: Put different fruits outside and count bird visits.
• Materials: Fruit pieces, outdoor area, notebook.
• Steps: Place fruits and observe for set times each day.
• Learn: Birds are attracted to certain foods.

138. How Does Water Travel Through Different Fabrics?

• Objective: See which fabric lets water pass through fastest.
• Materials: Cotton, nylon, wool scraps, water, funnel setup.
• Steps: Pour water and time dripping through each fabric.
• Learn: Weave and material affect water permeability.

139. Which Toy Car Goes Farther with Different Weights?

• Objective: Add small weights to toy car and test distance traveled.
• Materials: Toy car, small coins, ramp.
• Steps: Run car with different weights and measure distance.
• Learn: Weight changes momentum and friction effects.

140. Test How Fast Paper Burns with Different Thicknesses (Demo)

• Objective: Observe burning speed differences between thin and thick paper (adult demo).
• Materials: Thin and thick paper, safe heat source, adult supervision.
• Steps: Light equal sizes and time burn rate.
• Learn: Thickness affects burning speed (adult-only demonstration).

141. Make Colored Rain with Shaving Cream

• Objective: Demonstrate precipitation using shaving cream cloud and colored water.
• Materials: Jar, water, shaving cream, food coloring.
• Steps: Fill jar with water, put shaving cream on top, drop colored water and watch fall through like rain.
• Learn: Clouds hold water until heavy enough to fall.

142. Which Shoe Material Gets Wet Fastest?

• Objective: Test water absorption of leather, canvas, and synthetic.
• Materials: Shoe samples or materials, water, measuring cup.
• Steps: Pour equal water and observe soaking speed.
• Learn: Materials have different water resistance.

143. How Does Density Affect Layering Liquids?

• Objective: Make a density tower with honey, water, oil, and alcohol.
• Materials: Honey, water, oil, rubbing alcohol, clear glass.
• Steps: Carefully layer liquids to see separate layers.
• Learn: Liquids layer by density.

144. Which Type of Seed Produces the Tallest Plant?

• Objective: Compare beans, peas, and sunflower growth in same conditions.
• Materials: Seeds, pots, soil, water, sunlight.
• Steps: Plant and care same way, measure height weekly.
• Learn: Species grow to different heights under same care.

145. How Does Friction Affect Sliding in Snow vs. Grass?

• Objective: Roll a toy on a snowy surface (or simulated snow) and grass to compare distance.
• Materials: Toy sled or car, grass patch and snowy patch (or cloth simulating snow).
• Steps: Slide and measure distance.
• Learn: Surface conditions change friction.

146. Make a Simple Spectroscope (Paper Tube)

• Objective: Look at different light colors from bulbs or sunlight.
• Materials: Cardboard tube, CD, tape.
• Steps: Cut small slit, use CD to split light and observe spectrum.
• Learn: Light splits into colors by wavelength.

147. Which Material Slows Ice Melt Most in a Cooler?

• Objective: Line cooler with newspaper, towel, or insulation and test ice melt.
• Materials: Small cooler, ice, lining materials, measuring cup.
• Steps: Place equal ice and compare melt water after set time.
• Learn: Insulation helps keep things cold.

148. How Does Soap Affect Grease on Hands?

• Objective: Use colored oil to show how soap removes grease.
• Materials: Vegetable oil, food coloring, soap, water.
• Steps: Rub oil on fingertips, wash with and without soap and compare cleanliness.
• Learn: Soap helps remove oils.

149. Which Liquid Makes a Penny Shine Fastest?

• Objective: Compare toothpaste, vinegar, and cola on penny shine.
• Materials: Pennies, liquids, toothbrush.
• Steps: Treat pennies and compare brightness after rinsing.
• Learn: Some liquids remove tarnish quicker.

150. How Do Different Containers Affect Plant Growth?

• Objective: Grow same plant in plastic, clay, and metal containers.
• Materials: Three small pots of different materials, same soil and seed.
• Steps: Plant same seed in each pot and measure growth over weeks.
• Learn: Container material can affect soil moisture and temperature, changing growth.

Tips for a Great Science Fair Presentation

• Make a clear title and state your question or goal.
• Show steps, materials, and results with pictures or drawings.
• Use charts or tables to show measurements.
• Explain what you learned and one thing you might try next time.
• Practice your explanation so you can speak clearly to judges or friends.

Safety Reminders

• Always work with an adult for heat, fire, or chemicals.
• Wear safety glasses and gloves when needed.
• Keep food experiments separate from snacks and throw away after testing if not safe to eat.
• Clean up your workspace when finished.

Must Read: 166+ Kindergarten Project Ideas — Fun & Simple

Conclusion

You now have 150 fun and straightforward science fair project ideas made for 3rd graders. Each idea uses simple materials and clear steps so you can try them at home or school.

Remember, successful science is about asking a question, testing carefully, and sharing what you learned. Pick one idea that excites you, follow the steps, keep good notes, and have fun discovering science!

If you’d like, I can help you pick one project based on what materials you have, or create a printable project poster with title, hypothesis, materials, steps, results chart, and conclusion.

Which project do you want to try first?