# Monday Maths: Build a Tower

Today’s post is all about shapes – what shapes are strong, what shapes are weak?  It’s all geometry, and it’s possible to learn these things without going to school.

Think about the last time you saw some scaffolding.  For me, that was about ten minutes ago, since we’ve got some on our house at the moment.  What shapes can you see when you look at the scaffolding?

I’ll bet you can see squares and rectangles, but I’ll be shocked if you can’t also see triangles.  Lots of triangles.

There’s a reason for that, and it’s all in the maths.

If you take a rectangle, and apply pressure, you can change it into a parallelogram.  The top and bottom are still parallel, and so are the sides, but the right angles have disappeared.  The sides are still the same length – only the angles have changed.

The other thing that has changed is the height of the shape.  Try it yourself – make a square from straws, or pencils, and squish it a little.

Now, take a triangle and try to do the same.

You can’t do it – to make the triangle a different shape you need to change both the angles and the length of the sides.  That means if you only have a certain length to play with, you can’t change the angles, and that makes triangles strong.

Where’s the fun in all this, I hear you ask?

You’ll need some wooden skewers (or sticks, or garden canes, or pencils, etc), and some string (or sellotape), and a bag of sweets for each team.

Each team has to build a tower, with a little platform on the top.  Set a minimum height limit, or they’ll just build a bungalow!  When they’re done, start adding sweets until the tower collapses.  The more weight they can support, the more sweets they get.  It’s quite the incentive to build strong towers!

Tip: try it out for yourself using the same materials the girls will have, so you know how many sweets to buy!  For a healthier alternative, you could use fruit, vegetables, or some other item instead.

For added difficulty, you can provide weak materials like straws or newspaper, or don’t let them talk to each other out loud while building!

Afterwards, you can discuss which designs worked best.

For more on this topic, including links to fun videos and more sciencey explanations, see here.