Simple Machines: Wheels and Axles (and gears)

I guess I didn't take any pictures of our wheel and axle activities, but I'll include a few links.

First of all, I thought it was interesting to think of a wheel as simply a type of lever—one that rotates around 360 degrees. This video I mentioned on the Screw post, plus this other video about wheels, were really entertaining and informative.

This page is full of good ideas for wheel-related activities. They also made a waterwheel, which is something we did during our water unit a few years ago. It's really fun.

We chose to study gears along with wheels, and here are some gear activity ideas.

Another gear video.

We also talked about ratios and how they relate to gears.

And just in case you've ever wondered what the difference is between a gear and a sprocket, you can find out here!

To show how wheels can help you measure things, we made surveyor's wheels or measuring wheels, sort of like these described here.

We looked at the gears on our bikes and noticed how, just like with levers, increasing the size of the spokes or pedals can change your mechanical advantage.

We watched a couple videos about how wheels are even used in the natural world! For example, these rolling salamanders and caterpillars use the principle of the wheel to escape from danger.

And these leaf-hoppers actually have microscopic gears to ensure that both their legs spring at the exact same time when they jump. Amazing!!

Simple Machines: Pulleys

Pulleys are so fun! The concept of a block-and-tackle (multiple pulley configuration) was new to me, so I found it really interesting to test out why multiple pulleys make lifting easier. It makes sense when you think of the distance/effort tradeoff found in all the other simple machines!

This is a fun activity to help illustrate that concept.

And this is a good video about pulleys.

Here's a fun lesson plan with lots of good pulley activity ideas, like a pulley tug-of-war.

But really, the most fun of all was just experimenting with pulleys to lift things up and down from the balcony. We have these pulleys, which we used, and I borrowed a bunch of old spools (plastic thread spools and wooden spools) from my mom and just let the kids have at it. They came up with some great configurations. Daisy made a tiny paper flag and proceeded to hoist it up and down with great fascination and delight.

Malachi labeled a bucket "2000 Pounds" to make it more impressive :)

Abe had some elaborate multi-pulley system going on.

As did Sebby. Figuring out how to secure them to the balcony while still turning freely was kind of complicated.

I even found Marigold quietly inserting straws into spools and trying to make her own pulleys!

Another of Seb's efforts

Such a fun day!

Simple Machines: Levers

Onto the second category of simple machines: levers! First, we just talked about levers themselves (wheels and pulleys had their own dedicated days). Levers are so fun to play with. We found examples of the different classes of levers around the house. Here's one site that gives a description of each lever class. We had several books on this.

I also think this popsicle-stick chain reaction would be a fun activity to do when studying levers!

We had a great time playing around with levers: changing the length, position of the fulcrum, etc., and seeing what happened. It was pretty easy to lift Goldie! :)

Harder to lift Seb.

Even harder to lift Abraham!

Next, we made catapults. Making catapults is always fun, but we particularly liked this new design we discovered. Some catapults we've made in the past are kind of flimsy, but this one was sturdy—and easy enough to make that even the littler ones could do it by themselves, once they saw how the basic triangle component was constructed. The guy that made up this catapult has a great website with notes on castles and sieges and other catapult designs to try. If we'd been making these for a Middle Ages Unit instead of a Simple Machines unit, we would have tried out some other designs too.

You can find another catapult design (using a spoon) here.

We shot marshmallows and Hershey's kisses with our catapults. Fun!

It was a pretty impressive way to see the power of a lever!

And here's a bonus picture of the children using some levers on the "Archimedes Playground" at the Museum of Natural Curiosity. Fun!

Simple Machines: Screws

There are lots of fun things to learn about screws! We tried screwing several types of screws (pointed tip, blunt tip; threads close together, threads far apart; etc.) into wood so we could see how those differences affected the force needed to drive them in. We also compared the difficulty of pulling out screws from a styrofoam plate versus pulling out nails from that same plate. We saw that screws definitely hold things together more tightly than nails do!

We saw how this worked in another context using two milk jugs filled with water. One jug had a screwed-on lid and one had a snap-on lid.

The boys threw the jugs down onto the sidewalk as hard as they could…

and the snap-on lid popped off immediately upon impact! The screw-on lid stayed put.

Then we tried stomping on the same jugs. I think we eventually got both lids to come off, but it took a lot more force to get the screw lid dislodged!

Sebby got the milk carton stuck on his foot. We all thought that was really funny.

Next, we made two models. They were both different versions of screws: an Archimedes Screw and an auger. (I think the only difference between those two things is that an auger is usually used for solid material like dirt, and an Archimedes Screw is used for water and irrigation.) We kind of just made up the Archimedes Screw based on pictures, but some instructions can be found here.

The Archimedes Screw worked really well. You can see some of the water, after having been "screwed" up from the bottom bowl, dripping out into the top bowl. Very useful!

The instructions for making the auger came from a post here.

They were good instructions, but we didn't feel that our auger was a great success. The "threads" of the screw didn't fit tightly enough inside the bottle, but when we made them fit more tightly, they didn't turn freely enough. And there was too much give on the threads, so that the cereal could easily fall between them.

Still, we managed to get a few rice crispies up the screw into the upper bowl, so we got the general idea of how it worked. And we were lucky enough to encounter an actual auger doing work on the highway nearby a few days later, so that was exciting! :)

We made these "edible screws" for our snack using string cheese and refrigerated crescent roll dough. I liked the way they show so clearly how an inclined plane wrapped around a central core makes a screw!

Bake them at 375 for 10 minutes or so.

Yum!

We got a lot of great ideas from this post. (The lady that writes these plans is awesome. We've used her Revolutionary War lesson plans and others, and they are always SO full of fun things to try.)

We liked this video about the screw and the wheel.

I thought about having the children make the toy helicopters shown here to demonstrate how a screwing motion can, by increasing the distance traveled, decrease the force with which something falls—but we didn't end up having time for that.

Simple Machines: Wedges

I don't know if wedges really deserves its own blog post…but here it is anyway. We experimented with pushing different shapes through a pan full of lentils to see which was easiest. It was pretty clear that the wedge did the best job of cutting through and moving away the material, and we could see why wedge-shaped plows are so effective in turning up soil.

I also let the kids experiment with cutting apples using different types of knives. They liked that. They could really feel how the thinner, sharper wedges sliced more easily through the fruit. We also tried biting through the apples with our front teeth (wedge-shaped) vs. our back teeth to see how the wedge shape helps slice rather than grind food.

Here are a couple more cute wedge activity ideas.

This post has some great resources too.

Simple Machines: Inclined Planes

Studying Simple Machines is one of those things every child has to do at some point, so there are tons of books, tons of lesson plans, and tons of other resources on how to teach about them. I don't think we did anything that extraordinary, but we had fun anyway. We spent a day on each type of machine, so I'll just show a few of the activities we did, most of which were suggested by books we read or lesson plans we found online.

Inclined Planes are a good place to start, since they're so basic, and they are one of the two larger categories that simple machines fall into. (The other being Levers.) We did some basic demonstrations, like dropping a hard boiled egg from a certain height and observing the force with which the egg hits the ground:

(a lot)

And then trying to find ways to reduce the force, using inclined planes. We managed to get some mostly uncracked eggs by rolling them down longer and longer ramps. It was a good way to illustrate the concept of trading force for distance.

We also measured force using a simple homemade spring scale (something like this).

We could see how a weight pulling straight down on the scale exerted a lot more force than a weight partially supported by an inclined plane.

Our favorite video explanation of inclined planes was this one. It's from a whole series on simple machines, but for convenience I'll link each machine's video on the corresponding blog post here.

Another thing I think would be fun to do for an inclined plane study is make a marble run out of toilet paper tubes and popsicle sticks, something like this. We have some marble run blocks, but it would be fun to experiment with how different angles of inclined plane allow the marble to reach different speeds, and how that affects the force and distance the marble achieves within the system.

This is a great lesson plan for learning about inclined planes. It also contains a good review/overview of forces and work, as those terms are used in physics.

If you want even more of a review, you can watch this video on friction and mechanical advantage—

and this one on work—

and this one on Newton's laws of motion.

Robotics and Simple Machines Unit Study—Schedule and Lesson Plan

(click to enlarge)

Yay! We are back at it, following a blissful several weeks with our new baby Theodore. I've known for a long time that the children would love a Robotics Unit, but I was a little nervous to get started because I don't know anything about robotics! Luckily we already had last year's Electricity Unit to build on, and then I had the brilliant idea of starting Robotics by learning about Simple Machines! I'd planned to have a separate unit on Simple Machines, but since robots are complex machines, often made up of several types of simple machines, it seemed to be a good fit here.

We absolutely loved learning about robots, and now the children all pretend to BE robots constantly. I like it because robots are good cleaners and washers and workers! And if they protest, I can just remind them that robots ALWAYS do the job they are asked to do. Unless they're badly programmed, of course. :)

One thing I learned from one of our books is that simple machines fall into two main classifications: inclined planes and levers. So screws and wedges are types or variations of inclined planes, and wheels-and-axles and pulleys are types of levers. For some reason that concept had eluded me before, but dividing them up that way helped them make sense to me in a new way.

Here's my Robotics and Simple Machines Pinterest page.