4th Grade Science Fair Projects: Fun Science Experiments for Kids

Looking to spark curiosity in your 4th-grade students? A science fair is the perfect opportunity to turn questions into experiments and creativity into confidence. From colorful chemistry reactions to DIY engineering builds, these 4th grade science fair projects are designed to be fun, hands-on, and classroom-ready. We’ve categorized the best ideas by theme—and added essential teacher tips to help make your next science fair a success.

Let’s experiment!

Top-Rated 4th Grade Science Fair Projects for Kids

Introducing students to a variety of science projects can help them find areas that resonate with their interests. Below are categorized themes with detailed project ideas suitable for 4th graders.​

Simple Science Experiments

These experiments are great for beginners and require basic household or classroom materials.

1. Blow Unpoppable Bubbles

Objective: Students learn about surface tension and how additives like glycerin can strengthen bubble films.

Blow unpoppable bubbles

Materials: Dish soap, glycerin, water, straws

How to Do:

• Mix water with dish soap and glycerin to create a bubble solution.
• Use a straw to blow bubbles and observe their strength and longevity.

Expected Results: The addition of glycerin strengthens the bubble’s surface, making it more resistant to popping.

2. Erupt a Lemon Volcano

Objective: Demonstrate an acid-base reaction using everyday kitchen items.

Erupt a lemon volcano

Materials: Lemon, baking soda, dish soap, food coloring, knife, tray

How to Do:

• Cut the top off a lemon and place it on a tray.
• Add a few drops of food coloring and a squirt of dish soap to the exposed lemon pulp.
• Sprinkle baking soda on top and observe the eruption.

Expected Results: The citric acid in the lemon reacts with the baking soda, producing carbon dioxide gas that creates a fizzy eruption.

3. Sink and Float to Explore Density

Objective: Students understand the concept of density by testing which objects sink or float.

Sink and float to explore density

Materials:

• A large container filled with water​
• Various small objects (e.g., coin, plastic bottle cap, cork, small stone)

How to Do:

• Fill the container with water.
• Predict whether each object will sink or float, then test and record the results.

Expected Results: Objects denser than water will sink, while those less dense will float, illustrating the principle of density.​

4. Test Sharpie Solubility

Objective: Investigate the solubility of Sharpie ink in different solvents.

Test sharpie solubility

Materials: Coffee filters, Sharpie markers, cups, water, rubbing alcohol

How to Do:

• Draw a line with a Sharpie on a coffee filter strip.
• Dip the end of the strip into water and observe the ink’s behavior.
• Repeat with rubbing alcohol and compare results.

Expected Results: The Sharpie ink remains unchanged with water but dissolves when rubbing alcohol is applied, demonstrating solubility differences.​

Biology Science Fair Projects

Great for exploring life science topics and introducing students to living systems.

1. Grow Bacteria in Petri Dishes

Objective: Observe bacterial growth from different surfaces to understand hygiene and microbiology.​

Grow bacteria in petri dishes

Materials: Prepared agar plates, cotton swabs, markers

How to Do:

• Prepare agar plates in petri dishes.
• Use cotton swabs to collect samples from various surfaces (e.g., doorknobs, keyboards).
• Swipe the swabs onto the agar, label the dishes, and incubate for several days.

Expected Results: Different surfaces will show varying amounts of bacterial growth, highlighting the importance of cleanliness.

2. Explore Tooth Decay Causes

Objective: Investigate how different drinks affect teeth by observing what happens to eggshells as a tooth enamel substitute.

Explore tooth decay causes

Materials: Eggs, cups, various liquids (e.g., soda, vinegar, water), toothbrush, toothpaste​

How to Do:

• Place eggs in cups filled with different liquids.
• Place one egg in each cup and let them sit for 24–48 hours.
• Observe any changes in the eggshells.
• Try brushing the stains off to simulate dental hygiene.

Expected Results: Beverages like soda and juice stain or weaken the eggshells more than water. This mirrors how sugar and acid can cause tooth decay.

3. Test Music’s Effect on Plant Growth

Test music’s effect on plant growth

Objective: Students explore whether sound waves or music type impact plant development, touching on environmental biology and botany.

Materials: Identical plants, music player, different genres of music​

How to Do:

• Place each plant in a similar environment with different sound conditions.
• Play music for two plants (different genres) for the same duration daily.
• Water all plants equally.
• Measure growth weekly for 2–3 weeks.

Expected Results: Some plants may grow taller or healthier with calming music, showing a potential effect of vibrations or frequency on plant biology.

Physics Science and Engineering Projects

Let students experiment with movement, force, and engineering design using real-world physics concepts.

1. Simulate an Earthquake

Objective: Learn how buildings withstand quakes using shake tables.

Simulate an earthquake activity

Materials: Jelly or gelatin tray, small building blocks or toothpicks, stopwatch

Procedure:

• Create a “shake table” using gelatin or bands to simulate tremors.
• Build small structures from blocks or cardboard.
• Shake the table and observe which designs hold up best.

Expected Results: Students discover which structures are most stable and why, highlighting engineering design principles.

2. Build a Lung Model

Objective: Teaches respiratory system mechanics through a tactile, working model.

Build a lung model activity

Materials: Plastic bottle, balloons, straw, rubber band, tape

How to Do:

• Insert a straw into a balloon and seal the connection.
• Place inside a cut plastic bottle to simulate lungs.
• Cover the bottom with another balloon (diaphragm).
• Pull the bottom balloon to simulate breathing.

Expected Results: The balloon “lungs” inflate and deflate, showing how air pressure works in breathing.

3. Build a DIY Thermos

Objective: Helps kids test thermal insulation and learn about heat transfer.

Build a DIY thermos activity

Materials: 2 containers, insulating material (cotton, newspaper, foam), hot water, thermometer

How to Do:

• Fill all containers with equal amounts of hot water.
• Wrap each with a different material.
• Measure and compare water temperature after an hour.

Expected Results: Insulated containers stay warmer, teaching heat transfer and insulation properties.

4. Turn a Potato Into a Battery

Objective: Demonstrates how chemical energy converts to electrical energy.

Turn a potato into a battery

Materials: Potato, copper and zinc nails, wires, LED light

How to Do:

• Insert one copper and one zinc nail into the potato.
• Connect wires from each nail to an LED.
• Use multiple potatoes for more voltage.

Expected Results: The potato battery generates a small electric current, demonstrating chemical energy conversion.

Chemistry Science Fair Projects

These chemistry projects mix fun reactions with scientific learning—perfect for curious minds.

1. Turn Milk into Plastic

Objective: Explore how molecules bind by making casein plastic from milk.

Turn milk into plastic activity

Materials: Warm milk, vinegar, strainer, molds

How to Do:

• Mix warm milk with vinegar.
• Stir until curds form, then strain.
• Mold the curds into shapes and let them dry.

Expected Results: The hardened plastic shows how natural polymers form, a basic chemistry concept.

2. Grow Crystal Names

Objective: Create colorful crystal structures.

Grow crystal names activity

Materials: Borax, pipe cleaners, jar, boiling water, string

How to Do:

• Shape pipe cleaners into names or initials.
• Dissolve borax in hot water, add food coloring.
• Suspend pipe cleaner letters in the solution overnight.

Expected Results: Crystals form on the pipe cleaners, teaching about saturation and crystallization.

3. Baking Soda and Vinegar Rockets

Objective: Explore chemical reactions and propulsion.

Baking soda and vinegar rockets

Materials: Film canister, baking soda, vinegar, paper for fins

How to Do:

• Wrap baking soda in tissue.
• Add vinegar to the canister.
• Drop in baking soda, quickly seal, and step back.

Expected Results: The canister pops off due to CO₂ buildup—teaching gas reactions and Newton’s Third Law.

Environmental Science Fair Projects

These projects explore sustainability and nature while building scientific responsibility.

1. See Coastal Erosion in Action

Objective: Understand how waves and rain reshape coastlines.

See coastal erosion in action

Materials: Sand, water tray, fan or hair dryer

How to Do:

• Create sand “coastline” in a tray.
• Blow with a fan to simulate waves.
• Observe erosion over time.

Expected Results: Sand shifts and forms new shapes, demonstrating erosion and environmental impact.

2. Capture Waves in a Bottle

Objective: Visualize how oil and water don’t mix—and create waves!

Capture waves in a bottle

Materials: Clear bottle, water, oil, blue food coloring

How to Do:

• Fill half the bottle with water and dye it blue.
• Add oil, seal, and tilt side-to-side.

Expected Results: The liquids don’t mix, and waves form—teaching immiscibility and wave behavior.

3. Water Quality Testing

Objective: Test and compare water from different sources.

Water quality testing activity

Materials: Water samples, test strips (pH, nitrates), notebook

How to Do:

• Collect samples from tap, pond, bottled, etc.
• Use strips to test and compare.

Expected Results: Students learn how pH and particles affect water quality and environmental safety.

Fun Science Fair Projects

These ideas are playful, creative, and guaranteed to spark excitement among curious 4th graders!

Fun science fair projects

• Dancing Raisins: Drop raisins in a fizzy soda. They rise and fall due to bubbles—teaches buoyancy.
• Rainbow in a Jar: Layer liquids by density (honey, dish soap, water, oil)—a visual and vibrant way to learn density.
• Static Electricity Butterflies: Use a balloon to lift tissue-paper wings by static charge.
• Magic Pepper Trick: Soap touches water with pepper—pepper scatters instantly.
• Color-Changing Flowers: Place white flowers in dyed water. Observe colors creeping up petals—learn about capillary action.

Tips for a Successful Science Fair Project

Helping students create meaningful, fun, and educational science fair projects starts with great guidance. Here are proven tips to help you and your 4th graders make the most of their science fair experience:

• Start with Curiosity: Encourage students to explore topics they find interesting. Passion fuels better projects!
• Provide Structure: Use worksheets to guide them through the scientific method—hypothesis, materials, procedure, results.
• Assign Partner Work: Let students team up—it builds collaboration and reduces workload.
• Do a Dry Run: Practice presentations in class. Help students articulate their findings clearly.
• Create a Timeline: Break the project into milestones to avoid last-minute rush.
• Encourage Creativity: Allow for visual boards, videos, or models—different learners shine in different formats.

Frequently Asked Questions

1. What is the best science project for 4th grade?

The best project is fun, hands-on, and easy to understand—like the Lemon Volcano or Potato Battery. These strike a balance between excitement and education.

2. What are the topics for science in grade 4?

4th-grade science typically includes:

• Earth and space science (weather, erosion)
• Life science (plants, ecosystems)
• Physical science (forces, energy, matter)
• Environmental science (recycling, pollution)

3. What are the top 10 science fair questions?

Here are 10 common and creative questions that spark great projects:

• How do different liquids affect plant growth?
• Which type of soil absorbs water fastest?
• Does music impact concentration?
• Can sunlight fade ink faster than shade?
• Which material is best for keeping drinks hot?
• What’s the best way to prevent fruit from browning?
• How can I clean dirty water naturally?
• Does hand soap brand affect bacteria removal?
• Can magnets affect plant growth?
• Which food molds fastest?

4. How to do a 4th grade science project step by step?

Here’s a simple, teacher-approved breakdown:

• Choose a topic (based on curiosity or curriculum).
• Ask a question (e.g., What causes bubbles to pop?).
• Make a hypothesis.
• Gather materials.
• Write and follow the procedure.
• Record results using charts, pictures, or journals.
• Analyze and conclude.
• Create a display board to present findings.

Use a worksheet template to make it even easier!

The Bottom Line

4th grade science fair projects are more than just a school assignment—they’re a chance for kids to explore the world around them, ask meaningful questions, and develop critical thinking skills in a hands-on way. These projects encourage curiosity, creativity, and confidence, making them an essential part of a child’s science education.

Whether you’re a parent helping at home or a teacher guiding students in the classroom, supporting a 4th grader through their science fair journey can be a rewarding experience. The key is to choose a project that sparks your child’s interest and allows them to take the lead in discovering how things work.

With the right approach, 4th grade science fair projects can turn into unforgettable learning moments that inspire a lifelong love of science.

Don’t forget to check out printable worksheets and experiment journals at Worksheetzone—they make organizing and reflecting on science fair projects easy and enjoyable!