Science activity
Lever Lab: Spoon Catapults & Pry Bars
Explore LEVERS! Build a spoon catapult, pry open a 'treasure box' with a ruler, and balance toys on a paper-cup seesaw. Levers help us lift, pry, and launch.
Materials and setup
- spoons
- pom-poms or marshmallows
- wooden ruler
- paper cups
- pencils
- rubber bands
- cardboard
- small toys for lifting
How this changes by age
Pre-K (ages 3–4)
Explore LEVERS! Build a spoon catapult, pry open a 'treasure box' with a ruler, and balance toys on a paper-cup seesaw. Levers help us lift, pry, and launch.
Steps
- Spoon catapult: hold the bowl of a spoon down on the table, place a pom-pom in the bowl, then press the handle and let go. The pom-pom flies! (Aim away from people.)
- Pry bar: wedge the tip of a wooden ruler under a closed shoebox lid and gently push down on the other end. The lid pops up.
- Seesaw lever: balance a ruler on top of an upside-down paper cup. Put a small toy on one end and push down on the other to lift it.
- Try moving the cup (the fulcrum) closer to the toy. Is it easier or harder to lift?
- Talk about it: a lever has 3 parts — the bar, the fulcrum (the thing it balances on), and the load.
- Tell a grown-up one thing that surprised you.
Learning objectives
- Identify the three parts of a lever: bar, fulcrum, and load
- Explore how lever fulcrum position affects lifting effort
- Build several different lever setups (catapult, pry bar, seesaw)
Kindergarten (ages 5–6)
All about LEVERS! Find levers around the house (scissors, tongs, bottle openers), test how fulcrum position changes the effort, and build 3 lever projects.
Steps
- Learn the 3 parts of a lever: effort, fulcrum, load. The fulcrum is the pivot point.
- Lever hunt: find 5 levers in your home. Examples: door handle, scissors, tongs, bottle opener, see-saw, light switch, broom.
- Build a balanced seesaw with a ruler on a pencil. Add coins to each side until it balances.
- Test fulcrum position: with a heavy load on one end, move the pencil-fulcrum closer to the load. Is lifting easier or harder?
- Draw and label each lever you found, marking where the effort, fulcrum, and load are.
- Tell a grown-up one thing that surprised you.
Learning objectives
- Identify the effort, fulcrum, and load on any lever
- Find lever examples throughout the house
- Test how fulcrum position changes how easy lifting is
Early elementary (ages 6–8)
Study the 3 CLASSES of levers (1st, 2nd, 3rd class) and what each is good for. Build an example of each class and test mechanical advantage.
Steps
- Learn the 3 lever classes: 1st class (fulcrum in middle: seesaw, scissors), 2nd class (load in middle: wheelbarrow, bottle opener), 3rd class (effort in middle: tweezers, fishing rod).
- Find or build one example of each class. Draw each and label effort, fulcrum, and load.
- Test mechanical advantage with a 1st class lever: use a ruler on a pencil. Place a stack of coins as the load 5 cm from the fulcrum, and push on the other end at 5, 10, 15, 20 cm. How does effort change as the effort arm gets longer?
- Calculate: mechanical advantage = effort arm length ÷ load arm length. Try several positions and record results in a table.
- Write a paragraph: when would you want a 1st class lever vs. a 3rd class lever? (Hint: 3rd class trades force for SPEED — think tweezers and fishing rods.)
- In one sentence, tell a parent or sibling what surprised you today.
Learning objectives
- Distinguish between 1st, 2nd, and 3rd class levers
- Calculate mechanical advantage from arm lengths
- Explain when to use each class of lever
Upper elementary (ages 8–10)
Engineer a real lever-based device. Study lever classes, calculate mechanical advantage, then design and build a working catapult or grabber arm with a measurable performance goal.
Steps
- Review the 3 lever classes and their mechanical advantage formulas. Compute MA for each lever in your kitchen drawer (tongs, scissors, can opener, nutcracker).
- Pick a project: (a) catapult that launches a marshmallow at least 2 meters, OR (b) grabber arm (3rd class lever) that picks up a tennis ball from across a table.
- Sketch a labeled blueprint with measured arm lengths and predicted mechanical advantage. Identify which class of lever you're using.
- Build the prototype using cardboard, dowels, rubber bands, etc. Test it. Measure performance (distance launched / objects picked up successfully).
- Iterate: change the fulcrum position or arm length to improve performance. Re-test and record results.
- Write a short engineering report: design, MA calculation, test results, and one improvement for v3.
- In one sentence, tell a parent or sibling what surprised you today.
Learning objectives
- Apply lever-class theory to a real engineering problem
- Calculate and predict mechanical advantage before building
- Iterate on a lever design based on measured performance
Safety and evidence note
Read the full activity before beginning. An adult should supervise tools, heat, food, outdoor work, movement, and experiments as appropriate. Completion records that the activity was done; the child’s explanation, work sample, photo, or demonstration is stronger evidence of learning than a completion check alone.
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