Homemade Hovercraft

Well, it's not as cool as this one. But, it's pretty cool to see this little balloon hovercraft at work. And it just takes a minute to make. Instructions are here (or a thousand other places on the web.)

If you want to see it, you know…hovering (really just sliding around), you can watch this enthralling video.

Aerodynamics and the Forces of Flight

You can't swing a cat in the Aviation Education world without hitting something about "The Four Forces of Flight." There's no shortage of resources, but I'll include a few of our favorites.

This site is just great, all around. It talks about aerodynamics, forces, propulsion, materials, and so forth, and it has lots of good little animations and videos.

This is a very good discussion of the effects besides Bernoulli's principle that act on an airplane to help it fly. When I emailed my physicist brother about the fact that we were studying aviation, he immediately wrote back, "Did you run into any controversy about whether or not Bernoulli's principle really makes them fly?  There's a perennial 'Bernoulli!'  'No, angle of attack!' discussion, as if they both can't apply." Ha! And we HAD run into it. This site does a good job of showing that multiple factors are involved.

Here's another good overview site, with some activities.

This video about the four forces of flight was thorough, and entertaining.

This is a really fun lesson plan about flight. This is where we got the idea for our "drag chute," pictured above and below. It's a very effective illustration of how strong drag can be!

We also had fun making "Magnus Flyers," which we learned about from this video. They are very interesting little gliders! You can see Sebastian demonstrating how they work here:

Homemade Kites

On the first day of our Aviation Unit, after talking about the history of flying, we made kites. Kites are some of the first things that humans ever flew!

Honestly, there are only about two times in my life I can remember actually having fun flying kites. (This was one of them.) I think it is just rare that I've encountered the right conditions; wind that is strong enough and steady enough to make the kite work!

Anyway, this time was no exception. The kids ran and ran and ran, and their kites sort of…floated up and bobbed a bit before crashing down. There was wind! But not enough of it, apparently. However! We could still feel the forces on the kites, and the way the wind over the top of them created lift, and that was what we were going for, so it was worth it!

And the kites were fun to make. We used these templates, which made it easy enough for all the children to make their kites themselves.

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.