ingridscience

Add the ice and salt to the can.
Leave undisturbed for 15 mins.
Add more ice as it melts down.

The ice melts and starts to fill the can with water. The salt lowers the freezing point of the water, so the water can get below 0 degrees centigrade, making the bottom of the can next to the water very cold.
Frost (ice) forms on the bottom of the outside of the can where it is coldest, and dew (water) is on the top of the outside of the can (where there is no cold water on the inside).

There is always water in the air. When it is cold, what happens to the water in the air? It turns to a liquid and makes water drops (like the top of your can). See wet grass in the morning even though it has not been raining. Called dew. (Show image).
When it is really cold, what happens to the water in the air? It freezes into ice (like at the bottom of your can). This happens on the grass too - sometimes the grass is white in the morning. It is called frost. (Show image).

Note that this activity does not work so well in a very warm classroom.

Discussion of what wind is and does. Wind is moving air.
Wind is measured by where it comes from. Wind comes from different directions and brings us different weather.
We will make a wind vane to find out where the wind is coming from.

Tape the washers/coins near to the point of the triangle without sticking over the sides (for weight).
Balance the cardboard on your finger to find the balance point, then tape a tube over the balance point with the open end facing the outer edge of the cardboard. Put a skewer inside the tube and hold the wind vane up to catch the wind. The point of the triangle will face the way the wind is coming from.

Take the wind vanes outside to find out which way the wind is coming from. (May need a compass to check for north).

Look at live interactive map of Earth’s winds: https://earth.nullschool.net/#current/wind/surface/level/orthographic=-…

Temperature tells us how hot or cold it is.
Use a thermometer to measure temperature.

Optional: show chart of Vancouver temperature going up and down with the seasons.

You will each use a thermometer to measure temperatures.
Show the bulb that measures the temperature, which must be surrounded by the thing you want to measure the temperature of.

Start by measuring air temperature in the classroom, to check students are able to read the thermometers correctly.
Optional: write up/graph results and discuss why they are slightly different - air temperature varies slightly around the classroom; my thermometer are not the best, so are not calibrated so accurately.

Then do other temperature measurements:

The temperature of their finger, by placing their finger over the bulb of the thermometer. The bulb can be cooled again by blowing on it. This is useful for seeing the temperature rise, then fall, rapidly.

The temperature of hot and iced water (in insulated cups if you don't want the temperature to change quickly).
Optional: add salt to iced water to make it even colder (can be combined with the frost activity and use a metal can).

The outside air temperature (may be with another outside activity).

Optional: talk about digital thermometers, that look different from these ones, that are in weather stations and other equipment.

Print out the spot and cross image, or use the photo above.
Cover your right eye and hold the spot and cross image at arm’s length (or put your head at arms length from the computer screen), with your nose centred between the spot and the cross.
Stare at the cross, then slowly move the paper towards you/move your head towards the computer screen. Keep staring at the cross; keep your nose centred.
When the paper /screen is 20-30cm away from your face, the spot disappears, as the spot is over the blind spot of your left eye.
This can be a tricky activity - make sure you are staring at the cross the whole time.

We have a blind spot in each of our eyes where the optic nerve passes through the retina in the back of the eye. There are no light-sensitive cells in this area so it can not make images.

Hold the laser pointer up to the lens, and show how the light bends as it emerges from the lens.
The lens in our eye does the same thing, to project light from what we are looking at onto the back of our eye.

Use the lens to magnify newsprint or other small things.
(The lens in our eye can do the same thing).

Hold the lens in front of a white piece of paper to project an inverted view of a window or a bright light.
(The lens in our eye does the same thing).