Simple & Powered Machines Set

Structures

Structures is a simple machine in which individual parts are arranged to form a whole. All structures are under the influence of external and internal forces.

30-45 min.
Beginner
Grades 6-8
structures

Connect

5-10 Minutes

A structure is a construction in which individual parts are arranged to form a whole. All structures are under the influence of external and internal forces. Examples of external forces acting on a structure include the wind or the weight of trucks and buses passing over a bridge. An internal force could be the weight of a roof or the shaking of a large diesel engine on its mountings.
Choice of materials will affect the safety level of a structure.

Did you know?
In bridges, cranes, towers and even space stations, triangulation is often used to make structures rigid.

triangle-test

A frame structure is made from pieces called members. This frame is rigid because it is triangulated.

structures-model-frame-one

The forces that act on members are called tensile forces or compression forces. Tensile forces will stretch the structure and compression forces will squeeze the structure.

structures-model-frame-two

Members that are in tension are called ties; members that are under compression are called struts.

Common examples of structural principles can be found in scaffoldings, buildings and bridges.

Construct

5-10 Minutes

Build the following models. Use the Contemplate ideas below and on the Student Worksheet to learn about each model, one at a time.
Build J1 book III, page 30
Build J2 book III, page 31
Build J3 book III, page 32

principles-building-instructions-one

Contemplate

10-15 minutes

J1
This model shows a triangular structure. When the triangular frame is pushed or pulled the shape doesn’t change.
The triangular frame is rigid.

structures-one

J2
This model shows a rectangular structure. The rectangular frame is easily changed when pushed and pulled.
A rectangular frame is not rigid.

structures-two

J3
This model shows a rectangular structure supported by a cross member. The rectangular frame is prevented from changing when pushed and pulled by the cross member.
The cross members makes the rectangular frame rigid.

structures-three

Teacher Support

Students will learn about:
Triangular and rectangular structures with cross member support
External and internal forces
Frame structures and their rigidity

9686 Simple & Powered Machines Set (two students per set recommended)

Student Material

Student Worksheet

Download to view and share the student worksheet.

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