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This morning we had a school group visit us from Whakatane – about 30 year 10 students (14 and 15 year olds) – they carried out some activities in Chemistry, Earth Sciences and Physics. I led them (as two groups) in a physics activity involving catapults.

After doing the boring bit (talking about how energy is transferred from one form to another as the catapult is loaded and fired) we got to actually using the things. Our catapults have a metal arm, that can be bent back and locked in place. A projectile is placed on the arm, and then the arm is released. As it springs back into position, it throws the projectile about fifteen metres (if you get it right) across the room. Students can vary the release angle of the catapult, the mass of the projectile they put on it, and the effective length of the spring arm. They need to think through the best combination to get the projectile going the desired length.

As part of this session, I put a packet of sweets (lollies, candy, depending on your nationality – to me they are sweets) on the ground about 11 metres from the catapult and the rules were that if the group could get the projectile to land on the packet of sweets they could keep them. They could have as many goes as they wanted in ten minutes.

As I said, the students came through in two groups. The first group had a very careful, systematic approach. They varied one thing at a time, and carefully recorded the results – where the projectile landed in relation to the packet. After about eight minutes of narrowing down the possibilities, they scored a direct hit.

The second group took a rather different view of the problem. Essentially, this was to fire the catapult as many times as they could, and hope they got it.

Despite many more launches than the first group, the sweets remained very safe.

What the first group did is a lot like how science is done. (Well, it IS how science is done.) Carefully, and methodically. Think about what is being measured, and why it is important; the effect of one variable on another is considered. Slowly we uncover things. We may have a lot of failures on the way to developing an understanding about something, but they are not failures without purpose. In this way science moves forward. It is true that occasionally something a discovery is made seemingly at random, but this is not so often, and when it does, it is usually backed up by a lot of careful and systematic measurement. Like Becquerel did when he discovered radioactivity.