Natural Disasters Unit plan; Plate tectonics; Earthquakes

 

Our second "Summer School" unit was Natural Disasters, another perennial favorite topic among especially little boys (though my little girls have never complained about it either!). (Posts from the Old Days)

First was earthquakes, with this demonstration of plate tectonics on a molten cocoa earth (you just heat water with a layer of cocoa powder on top and then watch the convection currents break it up and move it around).

More plate tectonics and types of faults

Wow, some great buckling here

Testing different building heights and compositions for stability

Towers and liquefaction

Building earthquake-resistant structures (or trying to!!)

Clementine made gnomes, of course

Starting small :)

A little more daring

Ziggy was excited to try this earthquaking this tall tower I made (he anticipated what was coming)

Another gnome?? Does she do nothing but make gnomes? (Gnope.)

Some more avant-garde designs

Borax Crystal Snowflakes

My friend pinned this Snowflake crystal-growing project and I thought it looked fun, so I slotted it into our day about Avalanches and Ice Storms. (If you think that's a stretch, wait till you see me fit the Ice Castle in as a field trip! :)) We have grown a lot of crystals but we've never tried borax crystals before, and they are great! Fast-growing and beautiful. And I do love a project that's well-explained! We made a bunch of these for our own Christmas tree, and to give away as gifts to the boys' choir director, Primary teachers, etc. They were really fun to make!

Oh---also---we found you can reuse the borax solution to make more snowflakes. We used ours three times before it seemed like it wasn't working as well anymore. You just heat up the jar in the microwave until the water is hot enough to dissolve the crystals stuck to the bottom of the jar (3-5 min). Stir, and when the solution is clear again, put a new snowflake in and begin again. You can refresh it with a bit more water and another tablespoon of borax, if desired.

We used brown pipe-cleaner for our first batch, and they were pretty, but I think we liked the white pipe-cleaner better

And here they are on the tree! So pretty.

Avalanches and Ice Storms, and making freezing rain on a tile

One of the most interesting things we learned related to avalanches was about the invention of the "avalanche airbag." We did this demonstration with rice to show how lighter and bigger objects "float to the top" of an avalanche (it makes more sense to me to say that the smaller, denser objects sink to the bottom and push the bigger things up, but all our books described it as "floating," so maybe it is). These pictures don't really show what's going on here, but just put a bunch of toys and small objects into a jar full of rice and then shake the jar. The bigger things rise to the top and sit on top of the rice.

It's based on this principle that the avalanche airbags work. Here is one description, and here are a couple videos.

I think I mentioned earlier how I've never understood freezing rain and ice storms? Well, we learned that it's all about the right layers of air. We don't get them much here, but the pictures we've seen are so beautiful! Too bad they cause so much damage. 

Here's a good graphic explanation

Here's another diagram explaining the temperatures necessary for each type of precipitation.

One thing that's present in an ice storm is supercooled rain, which is basically rain that should be ice (it's at a temperature below 32 degrees F) but isn't, either because it has nothing to crystallize onto or because it hasn't had time to freeze. When this supercooled rain hits a cold surface, it freezes instantly onto the surface. We also learned about the types of ice, glaze (clear and smooth) and rime (bumpy and white because of tiny air pockets when it splashed up---it looks more like frost).

This demonstration uses supercooled water to make glaze on a ceramic tile. The instructions we had tried to make supercooled water by using distilled water (fewer dust/mineral particles in the water to provide a "hold" for ice crystallization) in a spray bottle and then removing the bottle from the fridge before it was totally frozen. We followed the instructions, but I'm not sure if our water actually became supercooled, or if it didn't but even water that is nearly supercooled works okay for this. Either way, it worked and it was cool!

To do this activity, you put a ceramic tile (or a smooth rock) into the freezer overnight. Pour distilled water into a spray bottle with the spray lid off. Let it sit, covered with a bit of saran wrap so dust doesn't get in, at room temperature for an hour or two. Then put the covered bottle in the freezer for another couple hours, until the edges are starting to freeze but the middle is still liquid. One of the times we did this, we let the bottle sit in the freezer too long and it froze all the way through. It worked fine to just let it sit on the counter for a little while, till it began to thaw, and then continue with the activity.

Insert the spray top into the liquid water in the bottle, and then remove your cold tile from the freezer and spray the water onto it. It should freeze into ice on the tile almost instantly!

The glaze formed by our "freezing rain"

You can see how we could slide this ice off in a thin, solid sheet. So interesting!

Wildfires and Lightning

Here are a few resources for wildfires and lightning:

In the past, we have had fun making "lightning" with balloons and light bulbs (as described here and here)

These videos here and here and here show a phenomenon called a pyronado or a fire tornado. We'd never heard of these before, but they are amazing! They are formed by convection currents, just like real tornadoes, but these currents are made by the fire itself rather by storm clouds. Really cool!

A video about volcanic lightning

Information on ball lightning (video quality here isn't that great, but we just don't have that many instances caught on video, I guess!)

The picture above is our little demonstration of how a firebreak works. You fill a pan with little pieces of crumpled-up toilet paper. Make a ditch in the middle. Then spray the toilet paper with food-colored water. You can watch the "fire" (red water) spread slowly through the toilet paper around it, but where there is no paper for it to spread through (the trench), it stops. This is the same way a firebreak (a ditch or other area cleared of trees and brush) stops a fire---if there is no fuel for it, the fire cannot spread.

Tsunamis (and other waves)

We quite enjoyed learning about tsunamis! Because of recent tsunamis in Japan and Thailand, there is a LOT of video footage of these huge waves. And as awful and terrifying as these events were/would be to experience, it is undeniably fascinating to see the pure power such enormous waves possess! Sam previewed the videos for us to make sure there was nothing too disturbing for the children to see. (In fact, if anything, they were a little TOO enthusiastic about the videos---I tried to impress upon them that real people are affected by these disasters, but it's hard to overlook the amazingness of those waves!) I said I hoped no one would have nightmares, and Malachi said it was going to give him goodmares. Hmm.

We did an activity to compare the origins of waves---regular waves, which are caused by wind, and tsunamis, caused by earthquakes. We got the idea for the tsunami-maker from this book.

You can find more resources on waves here.

To make your tsunami model, you cut out the bottoms of two nested foil pans (you could use just one, but two is more stable). Then cover the hole with duct tape. I can't remember what happened here---maybe we ran out of duct tape? You can see we used packing tape for the bottom side and duct tape for the top, so ours wasn't totally watertight.

Fill the pan with water, and proceed to experiment! First we set our pan down and blew on it with straws, making wind waves. We got some pretty big ones.

Then, we held the pan up and hit the flexible bottom part (the tape) from underneath to create tsunamis. You can really see a difference in the size and type of wave created by a disturbance under the water (an earthquake) rather than a disturbance above the water (wind). The earthquake waves are much taller and stronger because of the sheer amount of water they displace! We were inside the house (with towels) so I didn't allow the tsunamis to get TOO enormous, but I imagine you could do even more with this activity outside on a warm day! :)

Here are some of the tsunami videos we watched:

This video is a longer one that shows some of the footage from these other links. It's an entire program so it discusses how tsunamis form, etc. 

http://video.pbs.org/video/1863101157/

Some description of what caused it in this one

http://www.youtube.com/watch?v=foxww-tMoNg

The bigger wave comes in near the 5:00 mark

http://www.youtube.com/watch?v=IAa8BmuPqh8

This one gets interesting around the 4:30 mark

http://www.youtube.com/watch?v=I-KiGboUuy4

Newscast that shows some helicopter shots

http://www.youtube.com/watch?v=J2hUwFo6Vpc

http://www.youtube.com/watch?v=X3CleAc_iQ8

This is interesting because it shows what the waves look like before they get to land.

http://www.youtube.com/watch?v=-VcWF8dIDj4

http://www.youtube.com/watch?v=WRvcBBGIWio

http://www.youtube.com/watch?v=2rAJOo_VBhk

This one really shows the power of the water, but it does show some little kids screaming and crying about halfway through (they're safe, just scared)

http://www.youtube.com/watch?v=TRDpTEjumdo&list=RD2rAJOo_VBhk

http://www.youtube.com/watch?v=5-zfCBCq-8I&list=RD2rAJOo_VBhk

http://www.youtube.com/watch?v=vzvZy1zY8U8&list=RD2rAJOo_VBhk

Showing the aftermath

http://www.youtube.com/watch?v=MyTTrj4wKMU&list=RD2rAJOo_VBhk

Making a seismograph

I'm not totally sure I'm clear about the difference between a seismograph and a seismometer---I think seismograph is the older term, referring to a machine that actually outputs the data on paper (a seismogram). Now, they're usually called seismometers because they record the data digitally. If I've got that right, that would make our machine a seismograph. This was a fun project suggested in one of the books we read. It's easy to make---you just poke a hole in a paper cup so that a marker tip will fit through, like this:

You suspend the cup and marker from a string inside a box. Thread a long strip of paper through slits on either side of the box, and then gently shake the box as another person pulls the paper through.

Here is the seismogram our seismograph made! I think we recorded some large earthquakes. :)

Natural Disasters Unit Schedule and Lesson Plan

The children kept asking for a Natural Disasters Unit, but we'd already talked about several of these things (volcanoes in our volcano unit, floods and clouds and lightning and convection currents in our water unit, earthquakes and tsunamis in our rocks unit, etc) so I planned this unit to be a little less in-depth than it otherwise might have been. It's always fun to review things like volcanoes, though!

We also learned about several new things, one of the most interesting (to me) being ice storms and frozen rain---I've never understood why, if it's cold out, the "frozen rain" isn't just snow! Now I get it. We also made a barometer, which we've never done before and which we've found very fun to watch the past few weeks.

Natural History Museum

Sebby is SO HAPPY about this huge quartz crystal!

We went to the Natural History museum especially for their "special exhibit" on Natural Disasters, since we were about to start our Natural Disasters Unit. I'll try not to dwell with too much bitterness on the fact that the museum closed a half-hour before I thought they closed, so we got kicked out of the exhibit just as we were starting it by a zealous docent (although, as I pointed out to her, there were still 5 minutes left---"But we need everyone OUT by closing time," she replied implacably). As I said to Sam later, I've been kicked out of museums at closing time all over the world, so you think I'd be used to it by now, but I still get annoyed by that smug, not-my-problem attitude the docents always show as they sweep you toward the exit. It WAS my own fault for mis-remembering the closing time, as I thought I'd allotted plenty of time for the last exhibit. Still . . . what if a restaurant served you a lovely meal, then whisked it away mid-bite as the clock struck closing time? It was maddening.

Luckily (or not, I guess), the natural disasters exhibit wasn't that great anyway, as we saw while we were herded madly along through it to the exit. It was only a couple rooms, and had just a few rather basic "interactive" areas ("Feel this pumice!" "This slinky makes P-waves!") along with the usual tired Climate Change canards. So, no great loss.

The rest of the museum, which I had wisely (ahem) allotted most of our afternoon to, was great. We especially loved the minerals section, which had a great variety of specimens, many from Utah.

Erosion Table, always fun

Daisy making waves on the seismometer

Earthquake simulator (this "building" has cross-bracing and a tuned-mass damper on top to help stabilize it)

Beautiful topaz! We wish we'd found this!

Outside the museum