Here is a fun learning exercise - a bit messy so better outside. It's a chance to teach the kids some basic engineering principles, and have a competition at the same time.
The aim is to build a frame around an egg to try and protect it when it is dropped from a set height. The height is raised with each successful drop until one egg is left.
Excellent fun for a boy's birthday party.
Time: 1 hour
Age: 5-10's, Over 10's
Take an egg and use straws and sticky tape to build a frame around it. There are many, many different ways to do this.
The egg may not stick to the tape if it is straight from the fridge. Try wrapping straws around it to stick to.
She didn't make this herself!
Draw marks on a stick or on the wall at regular intervals, starting at 30cm and going at 15 cm intervals.
Start at the lowest mark. Drop the egg-frame and see if the egg breaks. Do this for everyone's egg. For all eggs that passed, drop them from the next lowest mark. Continue until one egg is left.
This one got to 10!
It helps to have a dog handy!
Extensions to the activity:
Instead of doing frames, make landing pads for the eggs.
Try to build a tower that will hold the egg. The highest tower that doesn't drop the egg or topple over wins.
For a harder challenge, put two tables of equal height about two feet apart, and tell the kids they have to build a bridge that spans the gap, and that successfully holds an egg at the centre.
A triangle is the strongest geometric shape, because it can't fold on itself. See below how the square can be folded, but the triangle can't. Look at the 3 dimensional triangle - it is very strong, but the square triangle can fold.
A wide base will mean less likelihood of tipping.
Look at how the forces work on each design. Straw strength is excellent in tension (pulling), not as good in compression (pushing), and not great in bending.