Do-Nothing Machine: printable worksheets

Choose the sheet for the learner's age. Each prints on a single page. Build the project first, then fill it in together.

Ages 5-7: Draw & tell

Name: ______________________Date: ____________

Homemade Science with Bruce Yeany · Do-Nothing Machine · Ages 5-7

My Do-Nothing Machine

Turn the handle and watch the two sliders.

1. Draw your machine from the top. Show the plus-sign tracks and the two sliders.

2. When you turn the handle fast, do the sliders crash?

◯ Yes◯ No

3. When one slider is in the middle, where is the other one?

◯ Also in the middle◯ Out in its own track

4. Draw the shape the handle made with the marker.

5. Is the shape a circle or an oval?

◯ Circle◯ Oval

Ages 8-10: Predict, test & record

Name: ______________________Date: ____________

Homemade Science with Bruce Yeany · Do-Nothing Machine · Ages 8-10

Test your machine, then measure the oval it draws.

1. Predict: if you crank as fast as you can, will the sliders crash in the middle?

◯ Yes, sometimes◯ No, never◯ Only if I go really fast

2. Stop with one slider in the middle. How far away is the other slider?

3. Draw the oval with a marker on the handle. Measure it the long way and the short way. Try each spacing twice.

4. What did you find out? Did the spacing change the oval?

5. Why do you think the two sliders never crash?

Ages 11-14: Explain & design your own test

Name: ______________________Date: ____________

Homemade Science with Bruce Yeany · Do-Nothing Machine · Ages 11-14

Use your trammel to explore the geometry and the lever inside it.

1. Use the word trammel to explain why the two sliders can never collide.

2. Stop the handle when the slider at the end of the stick is at the end of its trip. Name the fulcrum, the load and the effort, and the lever class.

3. Now stop it when the middle slider is at the end of its trip. What lever class is it now? Why?

4. Design a fair test of how pivot spacing changes the ellipse. Record the long and short widths and their difference.

5. In your test, what did you change, what did you measure, and what did you keep the same?

6. Where else might someone need to draw or cut a perfect ellipse?

Answer guide for grown-ups

Homemade Science with Bruce Yeany · Do-Nothing Machine · Answer guide

Any prediction is fine; it is tested next. (Result: no, never, at any speed.)
About 3 inches, the same as the distance between the two holes in the stick.
Open answer: look for effort and careful observation.
The long width minus the short width is about twice the hole spacing, so a bigger spacing makes a longer, thinner oval.
The stick holds the sliders a fixed distance apart, so when one is in the crossing the other is always out in its own track.

Each slider is a trammel: it can only move along its own track. The rigid stick keeps them a fixed 3 inches apart, and the crossing is smaller than that, so when one is at the crossing the other must be 3 inches out along its own track.
Fulcrum: the end slider (momentarily at rest). Load: the middle slider. Effort: your hand on the handle. The load is between fulcrum and effort, so it is a second-class lever.
First class: the fulcrum (the middle slider) is between the load (the end slider) and the effort (the handle).
Open answer: look for effort and careful observation.
Changed: the pivot spacing. Measured: the long and short widths of the ellipse. Kept the same: the marker position on the handle, the base, the paper, one full turn.
Examples: cutting an oval tabletop, mirror or picture frame (woodworkers use the same mechanism), drawing planet orbits, which are ellipses.