Structures that hold things up

Curriculum expectations

D2.2 — identify structures that are objects designed to support a load, including those acting as supporting frameworks for objects

D2.3 — identify materials that are used to make various everyday objects, including structures

D2.6 — identify properties of materials that enable the objects made from them to perform their intended function

Brief

This lesson asks you to find structures made to carry a load, to name the materials they are made of, and to say which properties of a material help it do its job. The museum offers one building element; the class looks at structures near school and home. ¹

What is holding this up?

Pick a roof, a bridge or a shelf and trace the path from the thing it carries down to the ground. Ask what each material along the way must be able to do.

Go deeper

Picture a big dome in Cairo. At al-Azhar, the dome rests on keel arches over old columns, and wooden beams brace the columns ². A keel arch is a pointed arch shaped like an upturned boat ² ³. The historian Richard Yeomans says this is much lighter than the solid brick piers of an earlier building ².

Think about it

Yeomans says the arches and wooden beams are much lighter than solid brick piers. If you were building a roof that must stay up, which would you choose, and why?

Into the museum

Keel arch: the arch shaped like an upturned boat, and where it appears in Cairo's buildings.
al-Azhar: the building whose dome rests on keel arches.
al-Aqmar mosque: a front with three keel-arched niches.

Try this

Build a small arch or bridge from blocks or paper and load it with a book. Compare how it carries the load with the keel arch on this page.