Kids College 09

We are part of the action this year for kids ranging from 4th to12th grade.  
Morning and afternoon classes, 3 hours each, makes for a full day.

One of the topics was Cryogenics, the really cool science.

We were so busy we didn't take many pictures but you can see some of the experiments we did on the Cryogenics page.
They thought it was really cool (77 degrees K).
Everyone enjoyed liquid nitrogen ice cream.

Here is a video of one of the experiments we did.  
We put an couple of hundred cc's of liquid nitrogen into a two liter plastic pop bottle.
Put the lid on and quickly dropped it into a 5 pound coffee can with about 2 inches of water in it.
Covered the whole works with a 5 gallon plastic bucket and got back about 120 feet. 
You see the result. 
Calculations based on measurements we made give a peak height for the bucket of 88 feet. 

Liquid Nitrogen Explosion 

You should be aware that fragments of the bottle landed more than 70 feet away from the launch point.
So get way back if you decide to repeat this.

We did take the class pictures.  
Wait till you see what we do with pictures later in the week.

We challenged them with the Eight Queens problem at the end of today's class and had several of them find multiple solutions.

If you want to try it yourself there are the rules.
In a standard game of chess the queen is the most powerful piece
It is able to attack any other piece anywhere in its row, column, or either of its diagonals.
The problem to be solved is to place 8 queens on the chess board with none of them attacking any other.
If you successfully solve this problem mark each of the occupied squares.
Then solve it again without using those squares.
Repeat marking and solving until it can't be solved again.

And we had more ice cream.

We built and flew hot air balloons in another class.
First cut out the gores from 8 layers of tissue paper.
Carefully glue the edges together to make the envelope of the balloon.

They are beginning to take shape.

Test to make sure that all the glue joints are secure.

Carefully inflate them with hot air.
The winds were higher than we would have liked for the flights.
some of the balloons got a little scorched during inflation.

Up, up and away.
For the first flight they were tethered so the balloons could be recovered for another one.
Some made
only tethered flights so the kids could take them home.
Others were released to fly free either intentionally or accidentally.
Some of these were recovered, others were still high in the sky when we could no longer see them.

Not all the balloons made multiple flights.
When a gust of wind pushed this student's balloon to close to the burner it caught fire.
The only thing left was the wire that had been around the bottom of it.
We were fortunate that only three of them went into the sky this way.

We tried the game of  Nim today.
The rules are simple it is a game for two players
You start with three rows of markers (we used pennies) with any number of markers in each row
    Rows of 4, 5, and 6 are a good set to start with
Each turn a player may take any number of markers from any one row.
Then the other player takes some from one of the rows.
They take turns
The player taking the last marker wins.

Galaxies, the atomic nucleus, and everything in-between is influenced by the fields and forces that we investigated. 

We studied Shocking Science where they learned about electrostatic forces, very high voltage and it's effects.
They built an electroscope from a pop bottle, a paper clip and a piece of mylar foil gift wrap.
Then used it to detect electric fields and learned how electroscopes are still used to monitor ionizing radiation. 
They were able to light a lamp with nothing more than a balloon, pie pan and a straw.

The Van de Graaff generator was a hit.
When they were touching the charged terminal their hairs were repelled from each other with this result. 

The charge wasn't enough to lift the braids but any stray hairs were standing straight out.

They also had the chance to see what electricity feels like!!
Everyone got to try it if they wanted to.
Some didn't look like they liked it but kept coming back for more.
We tried String Figures and some magic at the end of the class.
For instruction in how to do some of them go to The International String Figure Association site.
For an introduction to more easy string figures go here.
Click here for lots more string figure sites.
To learn some magic tricks you can go to this link.

The next day we were so busy investigating electricity and magnetism we only got one picture of one of the projects.
This is a telegraph key and sounder modeled after the original digital electrical communication.
It uses electromagnetism to detect the current from a battery when a switch is closed.  

The class also got to be part of a circuit, measure voltage and resistance, and power motors with batteries.
An electric meter let them see which kind of light used more power and whether a drill or a hair dryer took more when it was running.
They also saw the effect of eddy currents in copper and aluminum when a strong magnet moved near them.
And they had a chance to check out some very strong magnets and ferrofluid.
And they built magnet field viewers too.
Did I mention we were really busy.

We had time for a few puzzles too.
This time it was using matchsticks problems.
If you want to try them yourself here are some links
Puzzles with solutions:

Friday it was time for some light study.
Do you know what is going on when you take a picture? 
The kids got to look inside the process.

They took a camera apart to see what makes it "click".

Then they built a camera and used it to take a picture. 

The simple process we used created negative images.
I interchanged black and white digitally to make the positive ones.
Not bad considering the cameras were made of baking pans, paper and tape.
The exposures were 4 seconds so the camera and subject had to be very still.

In this one you can see the picture is reversed left/right.


Can you take a picture without using light?  They know how it can be done.
When we take light apart we can see what atoms are in the source.
And you can do it with just an old CD or DVD.

They learned how we see in three dimensions (3D). 
Put on your red/cyan anaglyph glasses and you will see the classes in 3D.
At least the ones who were able to hold still for two exposures.
Here they are in plane (pun intended) old 2D looking at themselves in 3D.

The final challenge for the week was solving some Tangrams.
If you want to try some yourself figures and solutions can be found here.  
More figures and solutions. This time in French are here
And even more Tangram information here.

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