# Arches

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Arches
Have you ever seen an arch? An arch looks like an upside-down U. The arch has been used in structures for
centuries. Arches help support bridges and gateways. They’re used for doors and windows and for holding up
ceilings, roofs, and floors. Arches are still used in many structures today. Let’s investigate how to build an arch
and how its shape helps to make it strong.
Build arch model 1.1 in building booklet 1, but stop at step 1.

How many levels of bricks are across the center of the arch? __________________________________

Stand the arch up. With your fingers, press firmly on the center of the arch.
What happens? ______________________________________________________________________

Repeat this experiment with one partner holding the bases of the arch.
What happens? ______________________________________________________________________
Why? ______________________________________________________________________________
Continue building the arch to step 2.

How many levels of bricks are across the center of the arch now? _______________________________

Stand the arch up. Press down firmly on the center.
What happens? ______________________________________________________________________

Which arch model was stronger?
 first one
 second one
Why? ______________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
Now let’s explore how arches can work together. Begin building model 1.2 in the building booklet, but
stop at step 1. At this point, your model should look like a Y.

Place your Y-shaped model upside down on your table. Press down firmly on the middle part of the
model.
What happens? _______________________________________________________________________
Continue building through step 2.

Place the model upside down again and press down on it as before.
What happens this time? _______________________________________________________________
Why? ______________________________________________________________________________
Finish building the model.

Stand the model up. Press down on the model at different places along the top. Observe closely. What
do you notice? _______________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
What You Have Learned

When you press down on the center of a fully built arch, what do you expect will happen?

If you have more time, investigate arches further. What is the tallest arch you can make? The widest?
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