STEM Day Activities for Kids: 7–10 Easy Projects Using Simple Materials

If your kids love to ask “But why?” — congratulations, you’re raising little scientists. STEM Day is the perfect excuse to lean into that curiosity with hands-on activities that are fun, budget-friendly, and totally doable at home. Whether you’re homeschooling or just looking for something engaging to mix into your week, these projects will keep your little ones learning while they play.

Below are 7–10 simple STEM activities using materials you can grab from stores right here in Orlando — plus optional printables from our STEM Activity Packs you can add for even more learning.

1. Sink or Float Treasure Hunt

A super simple activity that teaches early physics.

Materials: A clear bin of water, Random household objects (spoon, toy, leaf, crayon, etc.)• STEM Observation Sheet Printable 

How to Do It: Kids predict what will sink or float, then test it out. Have them sort objects into two piles and record results on the printable.

2. Build-Your-Own Catapult

Perfect for engineering skills and hand-eye coordination.

Materials: Popsicle sticks, Rubber bands, Plastic spoon, Mini marshmallows or pom-poms

How to Do It: Stack and rubber-band popsicle sticks together, attach a spoon to the top, and launch!Challenge them to predict which angle shoots farther.

3. Color-Changing "Magic Milk" Experiment

A kid-favorite chemistry activity.

Materials: Milk, Dish soap, Food coloring, Cotton swabs

How to Do It:Place drops of color in the milk, dip a soap-covered cotton swab in, and watch the color swirl. Use the Cause & Effect STEM Worksheet (internal link) to record reactions.

4. Balloon-Powered Car

STEM + racing = always a win.

Materials: Straws, Balloons, Cardboard, Bottle caps, Tape

How to Do It:Cut cardboard into a small rectangle, tape on wheels, attach a balloon to a straw, blow it up, and let the car zoom.

5. Crystal Candy “Rock Candy”

Science you can eat.

Materials: Sugar, Water, A jar, A skewer or string

How to Do It: Make a supersaturated sugar solution, tie string around a pencil, lower it into the jar, and let crystals grow for 3–5 days.

6. Weather Watcher Station

A great one for homeschool weather units.

Materials: Paper cup• Straw String Paper plate• Marker

How to Do It:Create a DIY weather vane, track wind direction, and chart daily changes using your Weather Tracker Printable.

7. LEGO STEM Bridge Challenge

Great for all ages — siblings can collaborate or compete.

Materials: LEGO bricks, Small toy cars or figurines

How to Do It: Kids build a bridge strong enough to hold toy cars. Test how much weight it can handle before collapsing.

8. Growing a Bean in a Bag

A perfect visual for early biology.

Materials: Ziploc bag, Paper towel, Dried bean, Tape, Water

How to Do It: Wet the paper towel, put it in the bag with a bean, tape it to a window, and track growth daily.

9. Paper Airplane Aerodynamics Lab

Great for older kids who love experimenting.

Materials: Paper, Tape, Measuring tape

How to Do It: Fold 2–3 styles of paper airplanes. Test which design flies the farthest and talk about lift, drag, and weight.

10. Fizzy Lava Science Jars

Color, chemistry, and fizz!

Materials: Clear jars, Oil• Water, Food coloring, Baking soda, Vinegar

How to Do It: Layer oil + colored water in a jar, sprinkle baking soda, then pour in vinegar and watch the fizz climb.

Where to Buy STEM Supplies in Orlando

So you’re not driving around all day — here are easy spots that carry nearly everything on this list:

1. Dollar Tree (Lake Nona, Conway, Alafaya)

Great for popsicle sticks, balloons, baking soda, spoons, bowls, and experiment containers.

2. Target (Waterford Lakes, Millenia, Lake Nona)

Good for craft materials, LEGOs, food coloring, sugar, measuring cups.

3. Michaels (Waterford Lakes or Millenia)

Best for higher-quality STEM materials: rubber bands, science jars, beads, glitter, cardboard sheets.

4. Walmart (Sand Lake Road, Narcoossee Road)

Budget-friendly for almost everything — plus baking and household supplies.

5. Ace Hardware (Lake Nona)

Perfect for cardboard wheels, wood scraps, and DIY materials for older-kid STEM projects.

Recommended STEM Products for Kids (Ages 4–10)

If you want to take your STEM Day to the next level without creating everything from scratch, here are a few screen-free, educational, and kid-approved STEM products we personally love and use. Each one keeps kids busy, learning, and building real skills through play.

1. National Geographic Mega Science Lab

If your kid is obsessed with mixing, creating, or “making things explode” (in the safe science way 🤣), this kit is EVERYTHING.Volcano eruptions, crystal growing, geodes… it covers all the classic science experiments in one box and keeps kids engaged for hours.

2. Snap Circuits Jr. SC-100 Electronics Exploration Kit

This is the STEM toy that grows with your child.Kids build REAL circuits — lights, alarms, switches — all hands-on with no tools required. Amazing for building confidence and problem-solving skills.

3. Melissa & Doug Solar System Puzzle

A hands-on, beautiful way to introduce astronomy.Perfect for morning bins, quiet time, homeschool rotations, or independent play. Sturdy pieces, great for ages 4+.

Mama's Thoughts 💌

STEM Day doesn’t have to be complicated. With everyday materials and a little creativity, your kids can explore science, engineering, math, and problem-solving in ways that feel like play. Whether you try one activity or all ten, the goal is simple: make learning hands-on, meaningful, and fun.

If you want ready-to-print worksheets to pair with these activities, browse our STEM Printable Library — perfect for homeschool days, after-school enrichment, or a fun weekend project.