What is a ball?

I asked the children to share something they know about BALLS. This garnered some interesting, as well as predictable, responses! "Circle", "soccer", "throw it", "basketball", "football", "bounce it", "roll it", and so on. Then came the question: "When is a ball not a ball?" Answer: "when it's a football!" Looking at a circle - in this case a plate - shows that to describe a ball as a circle is only partly right. It's a circle no matter which way you look at it. A ball has properties other shapes do not - this we could test by playing with a variety of balls of all sizes and materials. Sports balls made a good discussion starter because each sport has different rules of play, which are partly dictated by what kind of ball is being used. There is a huge difference between a ping pong ball, a basketball and a volleyball. Each of these is driven in  different way - with a bat, with hands or with wrists, yet they are the same shape. A football though is thrown and kicked but it's shape makes the trajectory very unpredictable - unless you are a football player!

Playing with all the different balls was the best way to illustrate the variety out there!

The following week the children were given a sheet of newspaper and asked how you would make it into a ball. First we ascertained it did not behave like a ball - no bouncing or rolling. How to do it? Well before long the children had scrunched it up - it was instinctive for many of them - they did it before they could verbalise what the procedure was.

from flat paper to a ball

Making the perfect ball

left on its own, the paper would attempt to regain it's flatness so I had the children suggest how we could keep the ball shape. "Glue", "tape", "string", were offered and we settled on taping. Now this behaved like a ball although nothing had been aded to the sheet of paper - only the SHAPE had been altered. We bounced and rolled for a while, then made a ball out of clay to compare. Clay stays in the molded shape and can be made smooth so is a better ball in many ways.

comparing paper and clay balls

Finally we used our paper balls to knock down some empty soda bottle 'skittles' - we did pretty well there!

As an extra brainteaser I asked the question: "Can you make a circle out of toothpicks or straws?" The unanimous answer was "No!" but some children were able to say WHY. They conveyed the fact that the picks/straws were not 'bendy', using their hands to explain this if they couldn't come up with the right words. Well, as long as the circle is BIG enough, then the answer became "Yes we can!"

making a circle out of straight lines