# 11. The Peek-a-Boo and the Hand-waver

## Overview

This lesson introduces two new constructions, each of which uses an angle-fold in combination with a parallel-fold. In the Peek-a-boo, the motion of the angle-fold is hidden by the parallel-fold, so it appears to “come from nowhere.” The Hand-waver uses a series connection to move the angle-fold so the action is on the side of the page, not along the gutter. These two constructions are the basis for many of the pop-ups in commercial cards and books.

## Materials

For the class:

Pop-up books that use the “Peek-a-boo” or “Hand-waver” constructions

For each student:

• Scissors, tape, rulers, ballpoint pen, and Post-it™
• Peek-a-boo Template
• Hand-waver Template
• Worksheet: Peek-a-boo & Hand-waver
• Science notebook

As needed:

## Procedure

1. Make a Peek-a-boo. Provide each student with a Peek-a-boo template and show them how to make a Peek-a-boo. Provide time for them to explore what this construction does and how it moves.

2. Make a Hand-waver. Provide each student with a Peek-a-boo template and show them how to make a Hand-waver. Provide time for them to explore what this construction does and how it moves.

3. Peek-a-boo vs. Hand-waver. Ask students to compare these two constructions. They can use the Worksheet to record their findings. See a video exploring similarities and differences. A good way to compare them is to make a system diagram of each one.
Outcome: Each construction uses both a parallel-fold and an angle-fold. In the Peek-a-boo, the two pop-ups are in parallel, while in the Hand-waver the angle-fold is in series with the parallel-fold. As a result, the Peek-a-boo produces up-and-down motion along the gutter, while the Hand-waver uses the parallel-fold to move the motion to the middle of the page.

4. Finding hand-wavers and peek-a-boos. Provide commercially made pop-up books that have these constructions. Students should look through these books to see how professional paper engineers have used the same constructions they have just made.

5. Extensions. Here are some experiments and design challenges: How long can the Peek-a-boo’s flag be?

## Peek-a-boo Template

peek-a-boo template.doc

## Hand-waver Template

hand-waver template.doc

## Peek-a-boo & Hand-waver Worksheet

Peek-a-boo & Hand-waver.doc

## Troubleshooting

Students may have trouble seeing the angle-fold in the Hand-waver. See a video that shows where the angle-fold is located, by making a similar angle-fold from a separate piece.