Well, the next thing we're going to investigate are gear systems. Where have you seen gear systems?

I have seen gear systems in a car, a race car.

OK what about you, Tina? Where have you seen gear systems?

I have seen gear systems in bicycles.

Bicycles. That's a really good example of gear systems, isn't it? Well, you're going to be taking a look at a gear system as well. Your system looks something like this. These are the materials that you have in your classroom. Let's take a look here. So in your system you've got a blue platform, large gear, small gear, a turning handle, and you have a pointer as well. I want you to take a look at that gear system and talk about-- with your partner-- what kind of interaction the gears are going to have when you turn the handle. I don't want you to try it yet. I just want you to talk about it and share your ideas. It's your time to share.

Welcome back. So what ideas did you have about how the two gears interact? Let's take a look here. And Lamar and Tina are going to talk about these gears. Tina, what do you think? If I turn this handle it causes what to happen?

The other wheels to turn the opposite way.

So if I'm turning this in a counterclockwise direction, you're saying that it then causes this other gear to turn in a clockwise direction. All right, so that's one of the things that we found out. There are some other things that you're going to have to investigate as you do this activity. So let's take a look at your activity sheet and just briefly talk about what you need to do. You have two different gear setups. Same gears, but the handle changes position. On box one your handle is on the large gear and on box two your handle is on the small gear. You need to talk about the number of teeth and rotations that each of those gears will have, the number of rotations that you observe, as well as the direction in which those gears turn. Down at the bottom part of the sheet you have a place where you can compare your results and there's even a challenge to ask you to go a little bit further and learn more about gears. So go ahead and get started. It's your turn and your time to investigate gears.

Welcome back. So what did you find out about how gears interact? Lamar and Tina found out some very interesting information. Lamar, you're going to talk about the box one gears. Tell us a little bit and while you're talking I'm going to demonstrate. How about that? OK, go ahead.

When you turn the large gear to the right, the small gear goes to the left. So large gear goes clockwise, small gear goes counterclockwise. And what did you find out in terms of the amount of times that it turned? If you turn the large gear, how many times? It went one time. Then how many times did the small gear go around?

Twice.

You thought it was going to go twice, right? That was your prediction. But in actuality how many times did it go around? Three times.

It actually went around three times, didn't it? Excellent. Tina, let's talk about your gear system here. And you were turning the small gear, is that correct? Yes. So you said if you turn the small gear to the right, the large gear will go to the left. And so we can demonstrate. Small gear to the right, large gear goes to the left. So clockwise for the small, counterclockwise for the large. And what did you find out in terms of the numbers of rotations? And I see here that you thought that if you turn the small gear one time that the larger gear would only go 1/2, right? What did you find out?

I found out that if you turn a smaller gear once, the bigger gear goes 1/3.

The bigger gear only makes 1/3 revolution. Now that's pretty interesting, isn't it? How many teeth did we have on these gears? What about the small gear, how many teeth? 10 teeth. Large gear? 30 teeth. So in Tina's box here, with the one that she did, we found out that one small gear equals 1/3 large gear. But on yours we found that three small gears equals one rotation. So a 3 to 1 ratio for box number one.

Gears interact in different ways, don't they? And we're going to see them in a variety of places. What I want you to do, though, is to take a look and continue to see where you're finding gears in your world. Well those are good observations.