## Overview

Each student is provided with materials for constructing pegboard mechanisms, and encouraged to make anything they want. Toward the end of the period, they share their constructions. The teacher uses the students' work to highlight the distinction between structures and mechanisms.

## Materials

For each student

• One pegboard base and three strips
• Fasteners:  three rivets, and three paper fasteners
• Science Notebooks

## Procedure

1.      Exploration with materials: Provide each student with a base, strips and fasteners. Encourage students to build whatever they can with these materials. If necessary, demonstrate how to join pegboard pieces. This video provides ideas on using fasteners, strips and bases.
2.      Whole-class meeting: Ask each student to show the class what he or she has made. It is likely that some of their constructions will be structures, while others will be mechanisms. Highlight these differences by asking of each one:
• Does it have any parts that can move separately from others? Or, are all the parts stuck together so each part can move only when all the parts move?
• Introduce the words mechanism (something that has moving parts) and structure (something that can only move as a whole).

3.      Group activity: Ask each group to sort their constructions according to the two categories, "structure" and "mechanism". What differences do they notice about the things in each category? See the video on identifying structures and mechanisms.

4.      Wrap-up discussion. Conduct a whole-class meeting to develop what students have learned.

• How can you tell if something is a mechanism or a structure?
• How could you change a mechanism into a structure?
• How could you change a structure into a mechanism?
Here is a video on converting structures to mechanisms and vice-versa

Outcome

• A structure has no moving parts.
• A mechanism does have moving parts.
• To convert a structure into a mechanism, you always have to remove fasteners.
• To turn a mechanism into a structure, you have to add fasteners.

5.      Science Notebooks: Students draw, describe and classify their constructions.