A wind-driven morning rain lashed our bedroom windows. Our youngest had spent a sleepless night in our bed, afflicted with a head cold; our oldest we could hear downstairs hacking up phlegm with a rattling cough. No one was going to school that day.
So, what do you do with such a day stretching before you, but bake oatmeal peanut butter chocolate chip cookies and do some science experiments. I pulled down a book from the boys’ shelf entitled Super Science: Forces and Movement, and began looking for some easy experiments.
I read to them: “There are two main kinds of force: Contact forces involve things touching each other, and pushing or pulling against each other. Kicking a ball is a good example. Distant forces are invisible forces, such as gravity or magnetism, that can work on an object without touching it.” So far so good.
Magnetism: The ancients knew about magnetism through the occasional discovery of naturally magnetized bits of mineral called, appropriately, magnetite, which would attract iron. These ‘lodestones’ must have seemed miraculous and inexplicable. To me, magnetism still is. Give me a couple of magnets – or better yet several – and I’ll sit playing with them for ages. As we all know, magnets have two poles – north and south. Two opposite poles attract, while two identical poles repel. And while simply holding two magnets in your hand and fiddling with them will show this (and how cool is it to feel that invisible force of repulsion as you slide your magnets around?), our first experiment set out to demonstrate this in an interesting way.
- At least 3 magnets.
- A piece of cardboard or a thinnish magazine.
- A length of string.
Put a number of magnets on a table (we used four), and cover them with a piece of cardboard or a thin magazine.Tie another magnet onto a length of string. Dangle the magnet above the others, and you will see it twist and bob about as if it were controlled by magic.Depending on the type and shape of your magnets, you may be able to flip them over so that some attract while others repel. The kids had a great time with this one.
Electrostatic force: Aka static electricity. When we were kids, my brothers and I would shuffle round and round the carpeted floors of our house, then zap each other with minuscule (yet surprisingly painful) charges of static electricity – an electrostatic discharge. We knew how to do it, but we didn’t really know why it could be done. What’s static all about, anyway?
To explain it easily for the kids: Everything is made of atoms, which are normally electrically neutral – that is, the positive and negative charges (protons and electrons) are equal in number. But electrons can jump from one surface to another. A balloon rubbed against your hair picks up extra electrons; place it against a wall, or your shirt, and the electrons will be attracted to the protons in the wall or shirt, and the balloon will adhere to them. Time to demonstrate.
- A balloon for each child.
- Small bits of paper.
- Hair (Or a fuzzy sweater will do.)
Place your small bits of paper on a table or on the floor. Blow up a balloon. Have your kids try to pick up the bits of paper with their balloon by placing it close to them. Chances are it won’t work. Now have them vigorously rub the balloon against their hair, and again place the balloon close to the paper bits. Magic! The paper jumps up and adheres to the balloon. The extra electrons you added to the balloon have attracted the protons in the paper.
Levers: This one is incredibly simple. Not like that tricky balloon and paper thing. Levers were one of the earliest machines. Their beauty is their simplicity, but kids are amazed at how they actually work, and how fiddling with the placement of the fulcrum changes the force needed to move an object.
- A chair.
- A strong ruler, a flat length of wood, a wooden spatula, spoon or something similar.
- An eraser, a block of wood, or something to act as the fulcrum.
Place your ruler (or whatever you’re using) under one leg of the chair. Ask your kids to lift it. Chances are, they won’t be able to. Now show them your fulcrum, and see if they can work out a way to use it. Older kids will probably already know. Placing the fulcrum under your lever, ask them to try lifting the chair again. It should be easy. Show how a large, weak movement at the long end of the lever produces a strong force at the short end. Encourage them to play around with the positioning of the fulcrum to see how it changes how much force is required to lift the chair.
Bonus: Use the lever as a catapult, and let the kids flick paper clips, nuts, paper balls or whatnot across the room. They’ll like that.
We actually did a couple more, which I haven’t included here. If you’re looking for more experiments to do with your kids, The Naked Scientists website has excellent ideas.
And oh, by the way, here’s the recipe we used for our oatmeal peanut butter chocolate chip cookies. Enjoy!