Building Civil War Pontoon Bridges

We discovered last time we did this unit that water bottles make great pontoons! Sebby was fascinated with all kinds of bridges at the time, so we went much more in-depth in our bridge and army engineering study than we might otherwise have. While I don't currently have anyone quite as obsessed as Seb was, spending an afternoon at the little creek building bridges is great fun for anyone!

Here are a couple videos about modern Pontoon Bridges:

SR-520 Pontoon Float-out

Floating Bridge Documentary

We split into teams so that each team could build their own bridge. I let them figure out their own designs and how to construct them!

Gus fell in the water almost immediately, of course. Luckily it was a hot day.

Daisy and Junie's first bridge was great! Strong enough to hold several marching soldiers.

Gus soon cheered up and was happily showing me how the cut on his toe was "almost better."

Daisy and Teddy tried a different bridge design, which worked maybe even better too. It was good to have some space between the pontoons for the current to go by and put less pressure on the bridge.

Their bridge was also nice and long!

The soldiers were able to sneak over to the enemy camp for a surprise attack!

Goldie and Junie tried a second bridge after seeing Daisy and Teddy's.

It was very sturdy!

Inventors and Inventions Unit

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Coming back from a new baby, I wanted to teach a unit that didn't need a ton of preparation. This one was perfect. We read a bunch of books about cool and funny inventions, talked about the technologies involved, played with some of the inventions we read about (like Slinkies and Super Soakers), and then I let the children do a lot of designing and iterating on their own inventions throughout the unit.

This is a really good resource for hands-on activities that help teach kids good design principles. I think they must be from a TV Show? It's called "Design Squad."

If you click on the link at the top left of that page, where it says "Videos," there are some fun videos showing the design process as well. Our favorites were the ones, like this one, where a dad engineers toys out of cardboard for his toddler son.

My brother is a patent attorney, and I would have loved to have him come as a Guest Speaker for our unit, but he lives in California. So we did the next best thing—a Skype call while he talked us through a PowerPoint presentation he'd made and sent ahead of time. It was so interesting! He's so good at explaining things and making complicated concepts seem simple. My older boys, especially, were fascinated and kept asking questions. He taught us about intellectual property and all its sub-categories—patents, copyrights, trademarks, and so forth.

Pictured above, we are on the call with him—a pretty typical picture of our homeschool with half the children in pajamas, me nursing a baby, people climbing all over each other, etc.

These are some "musical instruments" the children invented/built one day:

Automobile Unit Study

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This Automobile Unit is one I promised Abe ages ago. I'm not sure how he got so interested in cars, since I have hardly ever given a second thought to them, but somehow he did. And lots of this unit covered things he already knew! But it was fun for the rest of us to catch up with him a little. :) For Sebastian's part, he loves road signs and markings, so we made sure to loop those into our unit as well.

We spent quite a long time covering all these things, and many of the days didn't really have something to take a picture of, but there are a few other posts under the "Automobile Unit" tag.

Some miscellaneous links:

The difference between "brake horsepower" and "wheel horsepower"

"Bloodhound SSC" is the car that's trying to break Thrust SSC's speed record

This place sounds really cool. The boys say they would love to go there someday!

Car Talk! I used to love listening to this show in the car on Saturday mornings when my mom and I were out doing errands.

Ideas from a unit study on the Model T Ford.

Model T coloring page.

And here's my Pinterest page for the Automobile Unit, with many of these same links.

We watched some carefully-selected episodes of "Top Gear" with the children, but man it was hard to find ones without swearing or crudeness! Too bad, because they loved that show. We also watched Disney's "Cars 2" and "Chitty Chitty Bang Bang" during this unit.

Speaking of "Top Gear," though, by FAR our favorite book of the unit was by Richard Hammond from "Top Gear." It's called Car Science and it was just excellent. It explained every aspect of how cars work, in an engaging way, without talking down to the reader, but in simple enough terms that I understood concepts I was totally baffled by in other books. I highly recommend it!

Assembly lines, industrial robots, and robotic arms

The most common kind of robot today, it turns out, is the robotic arm—the kind used in manufacturing. Unimate, the first robot, was made to work on an assembly line at General Motors. There are two main kinds of industrial robots: gantry robots (which move on an X, Y, Z axis, usually from an overhead frame) and SCARA robots which are fixed at the bottom and move with more degrees of freedom. You can see a comparison of the different types here, and also here and here.

We watched these two "How it's made" videos to see some robotic arms in action:

Circuit boards

Airplane wings

Really, almost any of the "How it's made" videos will show a robotic arm at work!

To illustrate the concept of assembly lines (each robot/machine/worker does one specific task and can therefore become maximally efficient at it), we decorated robot-face cookies with an assembly line. Each person put on one type of decoration and then moved the cookies down the line.

The children got pretty good at their jobs, if not quite as good as real robot workers :)

Next, we made Lego robots and had them make things on assembly lines. These little robot workers were so cute:

And so hard-working!

But Sebby's robotic arm (SCARA robot) was even more true-to-life.

Robot jaws and robot hands

We learned about the various components that make up a robot (we did this over several days because there was SO much to learn!). Things like: 

• Types of motors: electric (servo, DC, geared, stepper), hydraulic, pneumatic
• Muscle wire for push/pull motion
• Power: Batteries, circuit boards
• Actuators, effectors, controllers 
• Sensors (input, output, photoresistor, UV, sonar, radar, lidar, infrared, etc.)

This "can a robot tie your shoes?" activity is a good way to demonstrate some of the limitations that robots have when trying to do everyday human tasks.

There were a couple other activities we particularly liked. The first one was building this "robot hand." It is constructed very simply out of cardboard, strings, and drinking straws. 

This is basically what we did, although these instructions make it seem rather complicated, and it really isn't. You can just look at the picture above to see how it all goes together: sections of straw on small squares of cardboard, with tape connecting them to the main hand. And then straws threaded through it all. It moves with surprising agility for such a simple thing! We loved it.

This version, slightly different, looks pretty cool too!

The other hugely successful activity was making these robots arms, or "robot jaws" as we called them. They are a pretty good example of a common type of effector used in robots. We found our instructions here (where they are called "monster jaws"). They are really easy and fun to make!

I think the coolest thing about these is how the criss-cross construction makes them able to extend and contract so drastically! They look short and tiny and then suddenly…HOMP!

They provided everyone with many hours of chomp-y entertainment :)

Simple Foil Circuits; Series and Parallel Circuits; Schematics

There are a lot of cool electronics kits you can get, and in fact we had been given some snap circuit kits earlier in the year, which I'd been saving for this unit---so we could have just started right in on those. I read lots of reviews on the snap circuits talking about how educational they were, and they ARE wonderful and we have loved them---but---my one problem with them is that they are somewhat far-removed from the actual workings of the electricity. By that I mean, all the actual wiring is enclosed in snap-able components, and while that makes for ease of use, it also makes the workings of the electricity somewhat more opaque (at least to me). I think once you understand what is going on, snap circuits are great, but for an introduction to circuits, I think there are better illustrations.

So, we started with what seems to me the very most basic form of a circuit: foil and a battery! (Here is a how-to video about foil circuits, if you need it.)

First we felt how the foil gets warm as a current passes through it

Then we added a tiny light bulb and watched it light up as electricity went through the circuit! (I will have a separate post about the materials we used for this unit.)

Next we set up circuits with batteries, bulbs, and alligator clips. We tried various configurations and learned about parallel and series circuits.

Parallel Circuit---note that the bulbs have the same brightness

Series Circuit---note the progressively dimmer bulbs as the current becomes weaker

The children also copied down a list of symbols used in wiring and circuitry schematics. They loved this---it's like a secret code!

Here are a few more resources for circuit symbols:

http://www.itclips.net/2012/04/03/going-from-schematic-to-breadboard/

http://dccircuit.wikispaces.com/01+Circuit+Symbols
http://guides.machinescience.org/mod/book/print.php?id=1312--scroll down on this page to see how a seven-segment display, like you see on digital clocks, etc, works. Very interesting.

Here's a short video about circuits

Also, these circuit worksheets from Teachers Pay Teachers are fun.

And we thought this article about circuits in your house was really interesting!

Freight Trains; Specialty Trains

This cool picture shows Bailey Yard, the largest railroad classification yard in the world. How trains are sorted and assembled is a question we'd never even thought to ask, but we loved learning about it!

This shows how the "hump" helps to separate and sort train cars

More sorting action

We also really liked looking through these pictures of types of freight cars.

We talked about some specialized trains like cable cars (we've always loved cable cars!) and trams (we've always loved trams!). Trams and Cable Cars are basically the same thing, in fact (though aerial trams can't usually ungrip from their cable), which is why aerial trams are sometimes called "cable cars" (like the one that goes across the Thames) . . . and streetcars are sometimes called "trams." See here, here, and here.

Just to keep things interesting, there is also the term "funicular"---a train which works the same as a cable car, except there are two cars that counterbalance each other as they go up and down a slope. Here are some beautiful pictures of a very steep funicular railway.

A video about how cable cars work

A video showing the cable car museum in San Francisco where the big motors are housed (we didn't get to go here when we visited SF, unfortunately---next time for sure!)

Rack-and-pinion railways, also called "cog railways," are different still (they are also used for steep slopes, though)---here's a video about rack-and-pinions.
And some beautiful pictures.

Diesel engines and Diesel-electric Locomotives

Seb's diesel engine diagram

Maybe if I'd ever been interested in cars, I would have known something about the internal combustion engine. But I haven't been, so this was all news to me. And as usual, once I begin to learn about something I start to see how interesting it is! I think the diesel engine is amazing!

It works much like the gasoline engine, but with much more air compression, so the fuel doesn't need a spark plug to make it ignite---it simply ignites when it comes in contact with the compressed (very hot!) air.

Ky's diagram---Abe's writing

Here's a great explanation of how the diesel engine works

Wonderful animations of diesel engines (you can slow them down and speed them up as desired)

Another animation of a diesel engine

A video explaining the diesel engine

Something a bit different---how locomotives are made

This old cartoon about How Diesel Engines Work is so awesome, I can't even describe it. We loved it! You have to watch it. Here's part I and part II.