Demolition

I decided to make the last day of this unit a study of other uses of explosives---they're not only for fireworks, after all. We read some fascinating books on demolition, and watched some videos:

http://www.youtube.com/watch?v=sK50So-yYRU&feature=youtube_gdata_player (this was the best one we saw---a great montage of different demolitions---the kids wanted to watch this over and over)

http://www.youtube.com/watch?v=ggg3C87UVCY&feature=youtube_gdata_player (the kids thought this was hilarious)

The night before, I had the unexpectedly brilliant idea of having the kids carry out their own demolition with blocks. It sounds like kind of a terrible idea, doesn't it? But it wasn't. It was so fun! The kids looooooved it.

First we surrounded the area with blue CAUTION CAUTION CAUTION tape (very important), and added some animal bystanders. Just to make it interesting. :) We wanted our building to collapse within its own footprint, if possible.

Our first attempt

The suspense was significant! My heart was pounding as we did our first countdown. :)

This one was pretty much a failure. The building wasn't sufficiently weakened beforehand. It hardly collapsed at all, as you can see.

Oh, I suppose I should specify how we made our "explosions": I just tied dental floss (leaving the ends long enough to trail out away from the building) around the most important blocks. The boys decided which ones those were (usually some central pillars on the first and second floors, or foundational blocks around the edges). When the countdown began, everyone grabbed a few strands of floss and, at the appointed time, PULLED outward. It worked pretty well, considering. (Considering what? That it wasn't dynamite, I guess.)

After that first try we got smarter, and more complicated. We had sequential explosions going on (this is a very useful technique, but tricky for certain ones among us to master---the older boys inspired much awe and fear with their insistent warnings and instructions). Unfortunately, a few animal bystanders were taken out in this explosion---well, let's not mince words: killed---but the children showed an admirable ability to put it behind them and try again.

This attempt was even better. Only a few casualties.

The final attempt! Sober and concentrating faces.

Demolition in action!

Anatomy of a firework

There are some really cool books and websites that explain how fireworks work. One of our favorite websites was this one, but there are lots more. This one was extremely helpful as well.  Inspired by this picture:

we decided to try to make our own fireworks models, with viewable cross-sections, of course.

I broke out the dried beans, colored lentils, and black sesame seeds. Ah, the joys of spontaneous creation and using what we have on hand. :)

The boys loved carefully including each part: the timed fuse, the short fuse, the lift charge, the burst charge, and so forth. Malachi and Daisy just wanted to pour lots of beans in theirs, and Junie (providing a nice symmetry) wanted to empty all the beans OUT.

We also found several diagrams/lists like the one above, telling about the names of various firework effects. You can even take a quiz here, though we found this one a little bit lacking in clarity. Still, it was fun.

Sparklers and Colored Fire

Probably my favorite part of our Fireworks Unit was this colored flame demonstration. We had talked about chemical compounds and their flame colors, but seeing them actually burn was just amazing. The first time we did this I used old mandarin orange cans to light the flames in, but then we wanted to do it again and glass bowls worked just fine too.

These are the chemicals we used. I had read that boric acid was available "at any pharmacy, as an eye antiseptic, or home improvement store, as ant and roach killer." I knew as soon as I read the words "readily available at your local ____" that I was in for trouble (I can never find anything that's supposed to be "readily available" at grocery stores etc.). And sure enough, none of the ant killers at Home Depot listed boric acid as an ingredient, and the lady at Walgreen's Pharmacy said she never carried it anymore. BUT, I lucked out and found it in this huge container at IFA (it's used for an eyewash in horses, apparently). IFA also had this antifreeze, brand-named HEET, which is just methanol. (I also saw some at 7-11.) Methanol is what you use to mix with the other chemicals since it gives you a nice clear blue flame. You just pour a little bit of each chemical (they're powdered) in your container, pour methanol over them, stir each to dissolve, and then light them.

We ordered the lithium chloride online here.

I just love this colored fire. I could have watched it burn all night. So pretty!

The idea for this next experiment came from this video here (subscription required). Basically, it just shows how they make sparklers: they use tiny bits of iron to create sparks. In the video he shows how you can file an iron nail and sprinkle the filings on a candle to make those same kind of sparks. We just decided to try it on the spur of the moment after watching the video, and I didn't think it would work since I didn't even know if our nails were made of iron or if I'd be able to get any filings from them. But they were and I did, and the kids  LOVED watching the sparks come from the candle. They even understood why it worked (more surface area=more oxygen, plus the smaller bits heat up faster) thanks to our study of combustion the day before.

The cast of characters

Success!

Thus prepared, we were able to enjoy our Fourth-of-July Sparklers at my mom's house even more! 

Hooray!

Color temperature, and fireworks in Art and Music

For Art class, Sam taught us about the Kelvin Scale and color temperature. He showed us how we can apply this knowledge to make things we draw (flames and fireworks, for example) look HOT. We reviewed what is the hottest part of a flame here: http://thehappyscientist.com/science-video/hottest-part-flame (subscription required).

We all tried our hand at it. L-R from top: Sam's example, Abe, Marilyn, Ky, Seb, and Daisy

Then we looked at and discussed the paintings and drawings in this article: http://hyperallergic.com/28387/the-art-of-fireworks/

And these:
http://www.1st-art-gallery.com/James-Wilson-Carmichael/A-Fireworks-Display.html

http://www.backtoclassics.com/images/pics/giovannipaolopannini/giovannipaolopannini_piazzanavonainrome.jpg

We all really loved these daytime fireworks (they rely on colored smoke effects instead of fire!):
http://www.dailymail.co.uk/news/article-2072514/Cai-Guo-Qiang-Chinese-artist-creates-fireworks-display-DAYTIME.html

We also listened to some music related to fireworks. There's Handel's Music for the Royal Fireworks, which is very regal and impressive, and also Debussy's Feux d'artifice (it's from Book II of the Preludes), which I'm partial to since I played it at one of my recitals in college. Both pieces are full of good discussion points: how does one re-create a visual effect without any visuals? Which musical devices make us think of explosions, smoke, sparks, etc? Why would the composer use the dynamics as he did? And so forth. Young kids are surprisingly good at talking about this sort of thing. It's really fun to see what they say.

Firework Chemistry

For our first day of the Fireworks Unit, we started with the basics: a discussion of elements and compounds and chemical vs. physical changes. There are tons of fun activities to do along with this, and I had a hard time choosing among them---we probably did too much in this one day (we went far into naptime), but we had a really fun time. If I were doing it again I'd take two days or even three for this part.

We had a big chart up on the wall where we wrote things down in either the "Physical Change" or "Chemical Change" column. We added to it all week, which was fun.

To go along with our books on this day, we watched a whole bunch of videos from "The Happy Scientist." To access most of his content, you need a subscription (I think it's $20 for a year)---which I think is totally worth it. He has really a clear and engaging style, and he has tons of great ideas for fun experiments to try. We all love him. Here are some videos that deal with chemical change/chemical reactions:
http://thehappyscientist.com/science-video/taking-marshmallow-apart (we did this ourselves, also)
http://thehappyscientist.com/science-video/why-things-go-bang (this was amazing to me: though I had learned the concepts in this video many times, I had never really understood them completely.  His descriptions finally made it all come together for me.)
http://thehappyscientist.com/science-video/fire-diamond

We made this sugar/caramel glass (Sam told us they use this in movies when they need to break lots of glass. Ours got overcooked a bit, but was still interesting.)

Dry ice is always fun (note Junie pointing at it in the background)

I have been at Halloween Parties where rootbeer was made (maybe at Rachael's birthday parties too?) but have never attempted it myself before. We used this recipe, with slightly less water, and it was great. We ended up using two batches of dry ice because it didn't seem fizzy enough, which was all to the good, as we got to witness more sublimation at work. :)

The film canister rockets were a big success. They work best with just the canisters, but it was to make the rocket bodies anyway, and see the boys gradually realize that the smaller they were, the farther their rockets flew. We experimented with both alka-seltzer tablets and the baking-soda-and-vinegar method. Abe finally perfected the latter by putting the soda in the rocket lid first (which tip I had read earlier, but didn't tell him---he figured that out on his own).

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My favorite part of this activity was watching the sheer anticipatory terror with which these people ran away after setting up their rockets to launch.