Masters of Disasters: Rocks, Crystals, and Fossils

 We started with the rock cycle.  This is easy to demonstrate with odds and ends of crayons.  You can crunch up the crayons (in a bag!) with a hammer, which simulates weathering and erosion.

You can pinch the bits of crayon together to form a crumbly sedimentary rock.

You can hammer the bits together (in foil) to form a stronger metamorphic rock.

And you can melt them (in foil, over a candle) to form an igneous rock.

 We spent some time looking at these kinds of rock from our rock collection.  Pretty fascinating, especially the crystals!

We did a several crystal growing experiments.

We did slow growing rock candy (sugar crystals) which I had shown them but not explained last week.

 Medium fast silicon crystals (from a "crystal garden" kit).  These formed over the course of the class.

Super fast, heat generating sodium acetate crystals in reusable hand warmers.

Seeing the three kinds showed how the speed of formation affects crystal size: slow crystals grow very large, fast crystals are tiny!

Then we looked at fossils.


At this point, we own a lot of fossils that we have found, been given, or bought!

To show the fossilization process, I had cut two "bones" out of spponges.  One I let dry, the other I soaked in brine, then let dry.  The dry sponge was still flexible, but the brined sponge was hard and filled with salt crystals, much like the soil minerals fill the microscopic spaces in bones and shells.

I pointed out the difference between direct fossils (like the whale vertebrae, petrified wood,and shark teeth), and impressions and casts, (like the shells and crinoids you can see in the light rock on the right and the dark rock on the left).

I allowed the kids to make casts of their favorite fossil by making an impression with sculpey (polymer clay) and then filling the impression with plaster.

It was a nice "last class" thing to let them take home their favorite fossil!

 Lastly, my favorite fossil experience has to be set up a few days before, but it is well worth it!

I collect bones from chickens, ribs, hams, and roasts.  I actuallyput them through the dishwasher to clean them up, then let them air dry.  I suppose you could also bleach them (something I do when I add wild found bones to our museum).

I mix up a big batch of plaster of paris, and hide the bones in bundles of plaster - about three bones per bundle.  I try to give each one a variety of bones, but the kids will love it even if all you have are drumstick bones!

After a few days, the plaster is dry and hard, and I let the kids chip out the bones with hammers.

Older kids like to use hammers with screwdrivers and paintbrushes to get the whole paleontologist experience!

Masters of Disasters: Earthquakes and Tsunamis

Dip-slip!

We started out reviewing kinds of faults by demonstrating with notebooks:

• dip-slip (one tectonic plate slips down)
• strike-slip (the plates slip sideways)
• oblique-slip (one plate slips down and sideways)

All these faults release energy when they move, of course, so we needed to talk about the Richter scale. 

I really liked this graphic because it gets across the idea that each number up the scale is 10 times higher than the previous number.

Since the tectonic energy (like all energy) moves in waves, I wanted the kids to see and feel the waves. 

We used a large pan of water that we tapped to show the waves.  I added a jar in the center to show how the solid core of the earth disrupts the wave pattern- incidentally, that's how they discovered the core was solid, as well as how they measured it's size.

To feel the waves, I had them sit on the floor with their eyes closed while I jumped.  I then had them move further and closer so they could feel the effects of distance on the strengths of the waves.

I also set up a seismograph using a shoe box and a weighted pen (those are washers taped to the top of a felt pen). I drew the paper through manually while the kids pounded on the table.

Then we looked at a process known as soil liquefaction. This happens during earthquakes when the water table is high.

We filled a plastic box with dry sand. I put my "building," a glass bottle of water deep into the sand. First they shook the dry sand, and the bottle fell over.

Then we moistened the sand and the bottle was locked in place (no amount of shaking dislodged it). Then we added more water. To the kids' surprise, the bottle fell over with only slight shaking! The waterlogged sand acted as a fluid when it was moved.

We moved outside to look at tsunamis.  We used a tub of water and some wooden blocks to look at how the shape of the wave mirrors the shape and movement of the plate underwater.

I had also set up a tsunami model wave pool. It's just an under bed box filled with water and with sand on one side (and sticks representing buildings) and a flat board under the water.

And then...

 How fun is that?!

Then it was back inside for the grand finale.

I had made a very large and fairly deep tray of jello. I put a layer of plastic wrap over it and let the kids pat it to make "earthquakes." The thing about jello is that you can actually see the lines of force, the energy waves, as they move through.

I handed out 4 sugar cubes to each kid and they all built "houses" on the jello. They counted down and... I patted the jello vigorously! Earthquake!!!

And then we peeled off the plastic and ate the jello, of course! 

Masters of Disasters: Earth and Volcanoes

I started out talking about the structure of the Earth (the crust, mantle, core, etc.) and we talked about how the Earth is not a perfect sphere.

To look at why the Earth bulges in the middle, we assembled these nifty contraptions.

You cut out two long thin strips of construction paper and punch

You thread the holes onto a pencil or pen so that you form a ball with the pen just inserted a little way into the ball (we stapled the part where the strips cross to give some stability).

When you twirl the pen, the ball flattens because of centripetal force.


Since we were already spinning things, I brought out a tray of 6 eggs - half hard boiled and half raw! I asked the kids to figure out which were which...

The trick is to spin the egg and stop it briefly. If the egg is hard boiled, it will stay stopped. If it's raw, it will start turning again because the inertial motion of the liquid inside will still be spinning.
Now for the act of faith! Once they agreed that a particular egg was hard boiled, I chopped it in half with one really quick hard blow from a heavy kitchen knife. They were correct!

  If you do it fast enough, you get a really clean cut and you can use the eggs layers as a model of the Earth with the shell being the crust, the white the mantle and the yolk the core. The core is not to scale (and you don't have an inner core), but the shell is. What I wanted the kids to see was that the crust is a very small, very thin layer of the Earth.

I then crunched up the egg a bit to show how the crust is in pieces (tectonic plates).

We looked at how the plates move using sponge continents in a pan of water.  We put the continents together, then heated the pan on the stove.  I added a bit of dye to visualize the heat driven currents.

This worked really well!  The only trick is to use push pins so the sponges don't get stuck together by surface tension.

A great interactive animation of this happening over the history of the Earth (including the future) is here.  And here is also a short video showing the last 600 million years.




We talked about how the plates move against each other, demonstrating with notebooks.

Transform: moving side ways, causing earthquakes.

Divergent: spreading apart to form a chasm (like the Rift Valley) or the chasm may open into magma which can form mountains (like the Atlantic mid-ocean ridge).

Convergent: smashing together to form folded mountains like the Himalayas (which we showed with layers of colored towels), one plate usually goes under the other(subducts), melting back into magma, and sometimes causing volcano inducing pressure (like most of the Ring of Fire).




Did someone say volcanoes?!

We built ours out of salt dough around a very small (1 cup) soda bottle.  I preloaded each volcano with a few tablespoons of baking soda, and then we took them outside.

Each kid gave their volcano a name, then I poured in the vinegar (spiked with soap and red paint).

Masters of Disasters: Hurricanes and Tornadoes

Last week we talked about the sun, this week we talked about water.  Where do we find water?  Where does it come from?  Where is it going?  The kids had a good theoretical grasp of the water cycle, so it was time to to get practical!

Water evaporates, but it needs energy to change phase.  You can feel this if you spread a thin layer of water (or alcohol) on your forearm.  You caan feel the liquid absorb heat from your arm so that it can jump to it's vapor phase!

Next up we made a cloud from water vapor: you take an empty soda bottle and add a little hot (not boiling) water.  A few drops of alcohol will make this more dramatic.

Light, then blow out a match and put this in the bottle.  You won't be able to see the smoke, but it's there, and it's critical - water needs something to condense on.  Seal it up and squeeze the bottle a few times. Cloud!

We also made rain ( hold a pot of ice water over a pot of boiling water), and lightning (balloon rubbed against wool in a dark room - for added pizazz, catch the spark with a florescent bulb!).

 We looked at cold air falling and hot air rising by using a smoking match in front of an open freezer and over a hot stove.

Then we talked about what happens when there is a lot of hot air rising and a lot of cold air falling at the same time.  I had enough kids that I had them demonstrate it by having half the kids go up the stairs while the other half were going down the stairs.

Nature handles this the same way we handle traffic- everyone goes to one side.  It doesn't matter if it all goes left or all goes right, all that matters is that it all goes the same way!  In a natural 3 dimensional system, this means spinning- this is why hurricanes and tornadoes spin!

We looked at hurricanes by using spinning water in a big pot.  We dropped in a paperclip on a thread to see where the strongest and fastest current was (near the edges) and we talked about the storm front and the eye.

We also looked at how the wind raised higher waves in shallower water by blowing through straws across a baking pan filled with varying amounts of water.



The favorite was an example of hot air rising: tea bag rockets!

Masters of Disasters: Big Changes

This series is focused on the forces that shape and change our planet.  I'm using it for 8-12 year olds, but I've done it with kids as young as 5-6.

Our planet is always undergoing changes, but when big changes happen quickly, we call them disasters: hurricanes, volcanoes, earthquakes, and the like.


One big force driving changes on our planet is the sun!


Yes, I realize there is a more accurate song, but I find that with young kids, it's better to use this song, and then explain that the gas on the sun is so hot that it's actually a new form of matter called plasma (because it's electrons are stripped away).

 Understanding exactly how the sun is affecting the earth is one od those things where a demonstration is worth 1000 lectures.

I like to take the globe into a dark place and use an incandescent bulb to represent the sun.  My globe has a conveniently accurate tilt, so it's easy to walk it around the "sun" and see how the parts of the earth receive more or less light at different points in the earth's orbit.

If you use an incandescent bulb, you can also show how distance and angle affect the heat each part receives (I have them put their hand on the globe).

 Now a question:  you can see how the sun gives heat and light to the earth, but what effect does that really have?  Could that light actually move anything on the earth?

Most kids don't think so, until I show them my radiometer. It was a cloudy day, so I had to take it outside to get it really moving.

The sun is really adding energy and moving things around on our planet!

Next question: what color is the sun?

We looked with a spectrometer!  Mine is store bought, but they are easy to make. You can see all the colors the sun is giving off!

We also looked at the light through prisms and water filled jars.

The jars help you see how light is bent and scattered as it passes through the atmosphere.  Air molecules scatter more blue light (which is why the sky is blue).  Water and dust tend to scatter the light evenly, so they look white.

This is why when you look straight up, the sky looks a darker blue: you are looking straight through the atmosphere.  When you look on the horizon, it usually looks paler because you are looking at the atmosphere at an angle and are seeing more of the low hanging water and dust.  Our summers are so humid that the sky looks nearly white at the horizon! You can see a little of this by looking through the jar straight on, and then at an angle.
Next up: wind!

What makes the wind?  One small part is the rotation of the earth.  I had the kids spin around with outstretched arms to feel the breeze.

Most of our wind is from the sun heating the atmosphere.   

How much the sun will heat things up depends on many factors, including the color of the earth beneath the air.    I used my scanning thermometer to look at the temperature of the black driveway and the light sidewalk: a 10 degree difference!

As the air warms, it expands, and as it cools, it shrinks. I like to have the kids model this by having them move slowly close together, then faster, bumping off of each other and taking up more space.

You can see this by blowing bubbles on a cold day.  Bubbles blown with your warm breath will rise, and bubbles made by the breeze from swinging your arms tend to fall.  This works best on a cold day without a lot of wind!

Masters of Disasters: Earth and Volcanoes

We started out talking about the shape of the Earth. It's mostly a sphere but not quite!

If you take two paper strips, staple them into an X, then place them on a pencil top, you can make a hollow sphere.

If you spin that sphere, you can see the sides bulge out, just as the Earth bulges at it's center from the force of it's rotation.

And while we're spinning things...

I have the kids find out which eggs are raw and which are hard boiled by spinning them. 

If you stop the egg briefly, a raw egg will start spinning again because of the momentum of the liquid yolk.  If it's hard boiled, it stays still.

I had them identify a hard boiled one, then, trusting to their skills, I chopped it in half with a large knife!

Fortunately, they were right!  The egg is a good model for the Earth: the shell is proportionately as thick as the crust, the white is the mantle, and the yolk is the core.  To be perfectly correct, the yolk would be a little smaller (and have an inner core).

Crunching the shell a bit, you can model how the tectonic plates connect to each other.

Looking a bit more at the tectonic plates, I had cut some continents out of sponges. 

I floated them on water, then put the pan on the stove.  To visualize the convection currents, I dropped in a little dye.

I had to use a push pin to keep the sponges from sticking to each other, but they separated and wandered about the pan, pushed by the heat driven motion of the water.

The kids had a general idea that the continents on our planet had moved in the past (they knew about Pangea), but the idea that they were still moving (at the rate your fingernails grow) and that the world would look different in a few million years were new and fascinating.

There is a great interactive animation here. And here is a straightforward video:

We looked a bit at plate boundaries using books to show the plate interactions.

 Transform: the plates are pushing past each other (causing earthquakes). 

Divergent: pulling apart like the Great Rift Valley or the plates in the center of the Atlantic.

Convergent: pushing together to form folded mountains like the Himalayas and the subduction zones in the Ring of Fire. 

I showed the mountain making by pushing together layers of towels - this was a good introduction to the layering of rocks and sediment as ecosystems change.

In my case, the blue towel was a layer of sea sediment, the yellow was desert sand, and the brown was a forest.

Very often convergent plates lead to  one plate going over and one going under (subduction).  The plate underneath melts back into Magma, but often presses up  against the other plate causing volcanoes!

Did someone say volcanoes?!

We used small soda bottles surrounded by salt dough.

The kids built them on the plates, and I loaded them up with a few tablespoons of baking soda.

Then the kids named them and we took them outside.


I'm using vinegar spiked with soap and red paint.