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Indoor activity

Marshmallow Catapult

Build a working catapult from straws, a spoon, tape, and rubber bands, then compete to launch marshmallows the farthest — a brilliant STEM challenge that doubles as a tasty snack break!

Ages 7-12 0-1 hours Education 9/10

Materials

  • Marshmallows
  • Rubber Bands
  • Ruler
  • Spoon
  • Straws
  • Tape

Illustrated Steps

1

Build the Base

Bundle four straws together and tape the ends tightly. Tape two straws upright at one end as the pivot support. This forms the catapult base.

2

Attach the Arm

Tape a spoon firmly along a single straw so the bowl extends beyond the end. This spoon-straw is your throwing arm.

3

Add the Rubber Band

Loop a rubber band around the two upright straws. Slide the arm under the band near the midpoint so pulling the spoon down creates upward spring tension.

4

Launch!

Place a marshmallow in the spoon, hold the base down, pull the spoon arm back, and release. Measure the distance and adjust the design to launch farther!

What You’ll Create

Engineer a real working catapult from everyday materials and use it to launch marshmallows across the room! 🏹 The build is simple enough for kids to tackle independently but satisfying enough to keep them tweaking and experimenting — adjusting the arm angle, changing the rubber band tension, and measuring distances. It is classic hands-on STEM with an irresistible reward built in.

Have fun!

  • 🎯 Set up targets (cups, hoops, zones) and score points for landing in each one.
  • 📏 Keep a score sheet and record your best distance after each tweak.
  • ⚙️ Try different arm lengths — does a longer arm throw farther?
  • 🏆 Challenge another person to build their own and compete for distance.

Why It’s Amazing

  • Physics: Children directly experience potential and kinetic energy — pull back creates stored energy, release converts it to motion. 🔋
  • Engineering Design: Build, test, measure, adjust — this is the real engineering loop. Every tweak is an experiment with a result. ⚙️
  • Measurement: Comparing distances with a ruler and recording results introduces systematic data collection in a fun context. 📏
  • Resilience: When the catapult misfires or launches sideways, that is a data point — not a failure — and figuring out why builds persistence. 💪

Pro Tips

For ages 6–8: Simplify the build — just tape the spoon directly to a single straw and loop a rubber band at the midpoint. Focus on the fun of launching, not precision engineering.

For ages 8–11: Introduce the challenge of a specific target distance. Measure and record three launches, compute the average, and adjust the design to improve it.

For ages 11+: Add multiple rubber bands and measure how tension affects distance. Graph launch distance vs. pull angle for a genuine science experiment. 📊