This summer we ran a day camp here in Elliott County for kids from 4th to 9th grade.
The older kids made hot air balloons from tissue paper glue and wire.

Then they launched them in front of the school.
Most flights were tethered so that they could recover them to fly again.
One free flight went over the school and landed safely so it too could take another flight.
     
And here is a video of one of the hot air balloon launches.


The younger kids took a look at how 3D pictures and movies are made.
Some systems require special glasses, red/cyan for this one of the junior campers.
If you can't find a pair but have red and blue markers and a piece of thin plastic like is used packaging you can make red and squares to look through.
Color the plastic as evenly  as you can for the best result.

Or you can cross your eyes while looking at this pair of  pictures.
With a little practice you will be able to see a third picture appear between them in 3D.

A little puzzling.  Nim, Tangrams, and eight queens challenged campers.

Here is a more or less typical moment in a class.

We did some chemistry to make some goo.

That could be used to blow these amazing bubbles.
             
Some parents got to try as well.

We tried some standard soap bubbles.

Then some kids were able to put others inside bubbles.


We all took a trip to COSI in Columbus Ohio.

Exhibits included hot air balloons, the brain and an air pressure canon. 
 
This huge granite ball is supported by water pumped under it.
Since it only touches the liquid there is very little friction and it can be turned with little effort.

Some of our campers got to help with the Electrostatic Generator show.
They found out that like charges repel and just what electricity feels like.
 
Standing in line for the Centripetal Generator.
.
This machine spins fast enough to pin you to the wall then when you are getting used to that the floor drops about 2 feet and you are stuck there.
When the rotation slows you slowly slide down the wall.





If you were a camper you might be able to recognize yourself on the ride in this video.Back at camp the morning group had built water rockets and now they were about to launch them.
   
If you know how far you are from the launch point just measure the angle from the ground when it is at apogee and you can calculate how high it went.
You can also get the elevation and azimuth from two points on a known baseline to make an even better measurement.

Sit on a skateboard and push two bowling balls back.
You have just demonstrated what makes a rocket go.
There are lots of ways to look at it:
For every action there is an equal and opposite reaction, unbalanced forces at work, force equals mass times acceleration, and conservation of momentum

Hold two liters of water out to your side, sit on a rotating chair and pull them in.
You will feel yourself spin much faster.
You have just demonstrated the conservation of angular momentum.
   
We investigated levers.
With the fulcrum in the middle the larger force wins.
But move the fulcrum toward one end and we have a mechanical advantage that lets a small force overcome a larger one.
The trade off is that the small force must move through a larger distance.
 
They had no trouble lifting me if I was close to the fulcrum and they were far from it.

We were able to put a known force on two eggs supporting one end of this lever.
In the first picture the eggs are holding up half of the weight of the lever and half of the weight of the camper.
By keeping track of the weight and positions of the campers on the lever we found that these eggs could hold about 200 pounds.

We also found that when one failed it made a mess.

A spinning gyroscope moves in strange ways.

If you are sitting on a chair it will turn when you try to change the axis of the gyroscope.
Very surprising and fun too.
 
As surprising as it may seem a light rubber ball and a much heavier bowling ball fall at the same rate.

We measured how fast the campers could run.
Look at that determination.
 
We used this device to measure how far away we were from several objects without going to them.
Again a known baseline and measured angles were all we needed.

Cartesian divers made from straws and clay or soy packets and paper clips were one of the last projects.


We did lots more too.
I think that all the campers had a good time.
I know I did.