Find out if you could be a Kung Fu expert. This is a great idea for a practical lesson. By dropping masses, students first find out the energy required to break a board. They then work out whether their moving hand has enough energy to match or exceed this – if so then, theoretically at least, they could break the board with their bare hand.
It’s a very engaging lesson and there's physics developed along the way, including plenty of opportunities for calculations. What's not to like?
Practical tips: Instead of a ticker timer, students could measure the speed of their hand directly using a light gate. Get them to hold a piece of black card vertically in their hand and then pass it through the sensor as quickly as possible. They can measure the width of the card more easily than they can measure the width of their hand, and if the card should happen to hit the sensor it will do less damage (and hurt less!) than a hand.
If you wanted to measure the mass of student’s hands more directly it could be done by displacing water in a Eureka can (1cm3 of water = 1g)
Actually breaking the board would make a memorable end to the lesson – any black belts out there prepared to give it a go?