Wednesday, April 29, 2009

Cartesian Diver

Fill 6 or more 2 litre plastic bottles with water. Have students form groups of 2 or 3.
Students need to use large container filled with water to float glass medicine dropper.
Have them adjust amount of water so that dropper just floats. In dropper shown 1 ml. of water works well.
Place the dropper in the bottle , tightly close lid and squeese the bottle with two hands. The pressure contracts the water in the dropper allowing more water to enter the dropper.

Friday, April 24, 2009


I have a number of science demos that I like to do with elementary students. Some require a little practice or prep time but you soon become confident with them.
I have never had a problem with this demo and have done it dozens of times but I still expect the glasses to go crashing to the floor.
We begin with a discussion of Sir Isaac Newton. There always seems to be one or two students who claim to have heard of him . I have been scared to ask how or where. I talk a little about gravity and the Law of Inertia.
An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
I mention pulling someone on a sled and how you have to use more energy to get the sleigh moving although sleds and toboggans are probably as rare today as hearing about 17th century physicists .
Then we count to 3 and I smash the stick.
Here are a few tips:
1. Originally, I saw this done with pins at the ends of the stick. I don't use them anymore and don't have to worry about losing them. ( I always thought the pins were cheating a bit.)
2. Do not let your significant other catch you using or even looking at the best crystal.
You can pick up some nice wine glasses at most dollar stores. Make sure you use wine glasses because regular drinking glasses don't have the same effect.

Tuesday, April 21, 2009

Land and Water

What percentage of the Earth is land?
Discuss names of continents and oceans with students.

Use an inflatable globe .

Designate 5 or 10 students as Catchers and position them around the room.

Assign an equal number as Markers. They record


Land ____ Water ____

on the classroom board.

Assign other students as Checkers. They will verify if the Catchers right thumb is on land or water.

Toss ball to first Catcher.

Catcher and Checker tell the Marker whether the Catcher's right thumb is on land or water.

The Catcher tosses the globe to the next Catcher.

After 10 tosses you will have recorded 50 or 100 catches. This will give you an estimate of how much of the Earth is covered with salt water.

Monday, April 13, 2009


One of our Signs of Spring is the return of the amphibians to lakes and ponds. In Nova Scotia the first frog to come out of hibernation is the Wood Frog. They make a quacking sound in the evening. After the Wood Frogs we hear the Spring Peepers. You can check out more frogs and frog info at: