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

• Pegboard bases (one per student) and strips (three per student)
• Two types of Fasteners: rivets and paper fasteners; box of 100 of each.
• Science Notebooks

Procedure

1. Exploration with materials: Provide each student with a base, three strips and fasteners (three each of rivets and paper fasteners). Encourage students to build whatever they can with these materials. If necessary, demonstrate how to join pegboard pieces using the rivet and paper fastener and how to remove the rivets (see a video ). . As students are working, you may notice that some students are building without bases. Encourage each of these students to use a base as a platform on which to build.

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 they can only move when all of them do?
• Introduce the words mechanism (something that has moving parts) and structure (something that can only move as a whole) and write them on chart paper.

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? The first part of this video shows sorting structures and mechanisms. The second part distinguishes among mechanisms.

Science Notebooks

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?

Introduce “pivot” as the word for a fastener around which a part of the mechanism can turn.

Outcomes

In the course of this lesson, students should

1.      gain skill assembling the parts of structures and mechanisms and

2.      learn to distinguish between mechanisms and structures, and be able to convert one into the other.

• 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.