Teacher Notes

Teacher Notes:

Arches

Learning Objectives:

Students will build arch models and use them to investigate the strengths and weaknesses of arches.

Key Ideas for the Unit

·  A structure has a particular job (function) to do.

·  The nature of its function will determine its shape.

·  The environment into which it has to fit will influence its design.

Discussion

·  Discuss with students how arches are used in the world around them. Are there any arches in the school or nearby?

·  When students press down on the first arch model, it breaks apart in the middle. When they hold the bases firmly, the arch can resist the downward force. This is because the arch transfers the downward force to the bases.

·  This same lesson is demonstrated with the “Y” shape of the second model. The additional beams give strength to the arms of the Y.

·  An alternative investigation can be carried out by pressing down on an upside-down Y, first on a table or desk top, and then on a piece of paper or other material. The friction between the bricks and the paper is often enough to resist the pressing force and keep the model together.