Hanger Scale
Word of the day: heavier
“Let's build a machine that tells us which thing is heavier, no guessing allowed.”
Grab
- a coat hanger with notches or a plain hanger
- two paper or plastic cups
- string or tape
- a door handle or cabinet knob to hang it from
- small things to weigh: blocks, crayons, coins, grapes
Do
- Tape or tie a cup to each end of the hanger. Hang it from a door handle. Check it hangs level.
- Put a block in one cup. Which side goes down?
- How many crayons does it take to balance one block? Count them in one at a time.
- Let them pick two mystery things. Guess which is heavier by holding them, then check with the scale.
The big moment
Hang a light thing far out and watch it hold up a heavy thing close in.
Ask (guess first, then try)
- Which side went down? Why?
- Were your hands right or did the scale surprise you?
What's going on (for you)
A balance compares two weights; the heavier side drops. It's a lever with the pivot in the exact middle, so it links back to The Magic Fork. Counting how many crayons equal one block is a first taste of measuring with units.
If they want more
Make the arms uneven by hanging one cup closer to the middle. Now a lighter thing far out can balance a heavier thing close in, just like the fork.
Look it up
Wikipedia: Weighing scale PhET simulation