## Overview

Students continue to redesign and decorate their MechAnimations and to develop the story the MechAnimation tells.  There is an interaction between MechAnimation and story: each inspires changes in the other.  For example, a development in the story may result in an addition to the MechAnimation. Similarly, a change in the way a MechAnimation moves may give a new story idea.

## Materials

• MechAnimations and Mechanisms from Lesson 10
• Cardstock – 100 sheets
• Corrugated cardboard– 50 sheets (8 ½ x 11") and 200 strips (1 x 11")
• Paper fasteners – 2 boxes of 100 each
• Markers, Post-Its™ & craft supplies for decorating MechAnimations
• Science notebooks

## Procedure

1.      Class meeting: review the lessons learned about distance and force:

• To make the output move further, move the floating pivot towards the fixed pivot.
• To make the input easier to move (requiring less force), move the floating pivot away from the fixed pivot.

Discuss whether it’s possible to do both at the same time. If not, then you have to decide which is more important – an example of making tradeoffs.

Introduce cardstock solutions to design problems. Both are described in videos.

2.      Designing and redesigning MechAnimations. Save most of the period for students to create the story to be told by their MechAnimations, and to redesign and decorate the MechAnimations to better illustrate the story.

Science notebooks: Students keep track of story ideas and MechAnimation development in their science notebooks.

3.      Class discussion of issues: Ask selected students to present their work-in-progress. The class has to guess what it represents and how it will move when the input is operated. The class should discuss the issues that came up, and how both the presenter and others have tried to address similar issues.

Outcome

Students describe their design process, including how they dealt with the tradeoff between increasing the distance traveled, and reducing the amount of force needed.