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Everyday Machines / Week 05 / Wednesday
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Week 05 · The Toilet

Wednesday

Look inside the tank
// A tank, a flap, a float and gravity
⏱ about 15 min

Wednesday: Look Inside the Tank

A grown-up lifts the tank lid and sets it down softly.

Rocket peeks in. "A chain! A flap! A floating thing!"

Raven presses the handle. "What do you notice first?"

Nova glows the water line. "Watch the float."

You need

  • A toilet
  • A grown-up to lift the lid
  • A flashlight
  • Paper and a pencil
  • Soap for after
Safety first
Only a grown-up lifts the tank lid. It is heavy.
Look in with your eyes. Hands stay out of the tank.
Wash your hands with soap when you finish.
The lid goes back on when you are done.

Watch a flush

  1. Your grown-up lifts the lid and sets it down flat.
  2. Look at the water level. Find the float.
  3. Press the handle and hold it a moment.
  4. Watch the flapper lift and the water drop.
  5. Watch the float go down, then come back up.
  6. Listen for the fill valve to stop.
For a grown-up
Set the lid on a towel on the floor.
Point out the chain, the flapper, the float and the fill valve.
Everything in the tank is clean water, but wash hands anyway.

What you saw

The chain pulled the flapper up.

Water rushed down into the bowl.

The float dropped with the water.

A low float opens the fill valve. New water came in.

The float rose with the water.

A high float shuts the fill valve. The hiss stopped.

THE REFILL
  • Tap a card.
  • Then tap its spot.
1First
2Next
3Then
4Last
WHAT HAPPENED?
  • Read the question.
  • Tap your answer.
What did the float do when the tank emptied?
What opens the fill valve?
When does the fill valve shut?
SentenceTrue or false?
The chain lifts the flapper.?
The float sinks when the tank is full.?
A grown-up lifts the tank lid.?
Hands go in the tank.?
WHY THIS EXERCISEThe float is the brain of the tank. It tells the valve when to stop.
Draw the inside of the tank. Label the flapper and the float.

You watched a machine work from the inside!

Tomorrow, we test the tank for a secret leak.

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