ingridscience

Distribute black bin bags, and ask students to tape over desk.

Distribute shallow tub and bottle containing very warm water. Add dry ice (2 pellets).

The following activities can be done with more or less emphasis on the weather phenomenon they are modelling.

Ask what weather phenomenon they have made. Cloud. Water vapour in the air cools to form water droplets.
(How dry ice makes this: super cold, becomes a gas at -80°C. The water vapour in the air (from the warm water in the tub), cools and condenses among the cold CO2 gas.)

Add more dry ice and hot water to the tub, then demonstrate making tornados: hold hand flat and upright within the cloud spilling out of the tub, then lift up fast. (Too tricky for most Ks, but they like to watch.) Watch this video to see how it's done (though not with the same equipment): https://www.youtube.com/watch?v=Yc-jNvNucQ4
The spinning air mass of a tornado is called a vortex. The air rotates around the funnel shape.
A real tornadoes is one of the most powerful forces on earth - winds up to 500km/hr.
They form when warm, moist air meets cool air and they start to spin. The air spirals up into a thundercloud. The low pressure inside (from fast winds) cools the air which condenses into a cloud.

Another weather feature is also a vortex but spins in a ring: called a microburst.
A microburst is formed when cold air descends to the ground fairly fast, then hits the ground and spins away in a ring.
This kind of vortex can be modelled with a pellet of dry ice inside a little warm water in a recycled water bottle. Squeeze and release the water bottle quickly and gently. It seems to work better as the dry ice bubbling subsides a little.

Knowing sunlight is a mixture of colours, we can figure out why the sky is blue, and sunsets are red.
Distribute glue sticks and flashlights.
Tell students the glue stick models our atmosphere. and the flashlight is the sun.
Challenge them to shine the "sun" through the "atmosphere" and look for a blueish sky colour, and a red-orange sunset colour.

Explanation:
Blue: Sunlight hits the atmosphere and is scattered in all directions (O2 and N2). Blue light is scattered more than other colours, so more blue reaches our eyes from all parts of the sky.
Red: As the sun gets low in the sky, its light passes through more atmosphere to reach you. Most of the blue light is scattered, so only reds/yellows reach your eyes.

Distribute glass of water, flashlight and white paper to each student or student pair.
Ask them: We have water and sunlight. What weather feature might we make?
Once they know they are looking for a rainbow, older students can be challenged to arrange the flashlight, jar and paper to make a rainbow, while younger students can be assisted in making one:
Hold the jar in the air just above the desk. Lay the paper down in front of the jar. Shine the flashlight at the water line from back a bit, maybe angling it downwards a little. Don't block the bottom edge of the jar with your fingers. The higher the jar, the wider the rainbow. If you tip the jar slightly, you can make multiple rainbows.

Show students the materials.
Give them their challenge: make a device that turns when they blow on it.
(They can be tested outside in the wind, but this is less reliable and satisfying.)
They do not need to make a stand for it - have them focus on the mechanics of the spinning part.

For younger/less mechanically-minded students, explain the key design components:
A 'pivot': parts that can rotate around each other.
'Blades' that can catch the wind: larger surface areas that the wind can hit and push against.
It is useful to refer back to these if students get stuck in their designing.

Optionally show different ideas for making a pivot (see second photo):
1. a skewer in an inverted tube/pen cap (to which the blades can be attached)
2. a skewer through a straw (to which the blades can be attached)
3. a blunt pin through an enlarged hole in a straw
There are other ways to make a pivot, but these are simple ones I have seen so far.

For some student groups the design components may be best introduced sequentially.
First all students make a pivot, then share each others’ designs.
Then students choose any of the pivot styles displayed, make their own pivot, then design blades to attach to their pivot.

For older and more mechanically-minded students, they can work with the materials for a while, before naming/explaining the parts.
After a while, naming and explain the design elements of 'pivot' and 'blades'. This will help students that are still to start on a design, and conceptually frame designs already in progress.

For Kindergarten students, provide them with tube-and-skewer pivot, cardboard, scissors and tape. Demonstrate how the tube spins on the skewer. Draw and name shapes that they could cut out of cardboard ('rectangle' and 'triangle' good to include), to tape to the tube. They can add more shapes if they want. Depending on how they tape the blades onto the tube, and so how floppy the blades are, they may need to be shown how to strap a strip of curved cardboard across two blades to hold them steady.

Allow students time to freely experiment, discuss ideas together (and share good ideas with each other, as all designers and architects do).
The Play-Debrief-Replay method for teaching works well for this activity - see notes in the resource.

If students are in need of help, either ask them to visit other wind machines that are spinning in the classroom, or help them focus on some ideas (e.g. see pivot ideas above).

Once they are done experimenting, review the different ways of making the key machine elements (pivot; blades to catch the wind)

During discussion, refer to uses of machines that turn in the wind:
Wind turbines are used to generate electricity: the energy in wind turns a blade which runs a generator to make electricity. Wind turbines are in greater use with increasing sustainable energy practices. Wind turbine diagram of parts: https://upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Wind_turbine_…
Wind pumps are wind machines that can be used to pump water for farming or for groundwater extraction. Photo of a wind pump: https://en.wikipedia.org/wiki/Windpump#/media/File:Wind-powered-agricul… Video showing wind pump mechanisms of gears and pump: https://www.youtube.com/watch?v=BugXmDxC0WM
Windmills were commonly used for grinding grain. They are complex machines of levers, wheels and gears. Windmills in the Netherlands: https://en.wikipedia.org/wiki/Windmill#/media/File:KinderdijkWindmills… Windmill diagram showing gears transmitting wind energy to millstones: https://tringlocalhistory.org.uk/Windmills/images/03/Schematic%202.jpg
Anemometers measure wind speed - cups that spin around a shaft. Using magnets, the number of turns is translated into wind speed.
Wind vanes have a blade that turns in the wind, but its position stabilizes to show the direction that the wind is coming from.

We will make a barometer to measure changes air pressure. Air pressure is caused by the molecules of air piled up on top of each other and pushing down. We do not normally notice these changes, but may have done if we have been in an airplane. The air pressure is quite a bit lower up high, so much so that airplane cabins need to be artificially pressurized so that we can breathe up there.

How to make a bottle barometer, which can show changes in air pressure:
Add the water to the empty drink bottle. Optional: add several drops food dye.
Insert the tubing into the bottle until one end rests on the bottom of the bottle and the other end hangs out of the bottle.
Suck on the tubing end outside of the bottle, until the water almost reaches your mouth.
Take your mouth off the end of the tubing and immediately plug the end with some clay/playdough. If the water level inside the tubing drops out of sight before plugging with clay, retry until the water line is high enough up the tubing to be clearly in view.
Watch the level in the tube for a little while to make sure the modelling clay makes an airtight seal on the end of the tube.
Add a piece of tape to the outside of the tube with a line on it, or on the wall next to where it is taped, to show the initial level of the water.

The level in the tubing will rise up and down as the atmospheric air pressure changes over several days:
Air pushes down on the water surface inside the bottle, which holds the water up in the tube.
If the atmospheric air pressure rises (usually associated with clear weather), the air pushes down more on the water surface inside the bottle, which pushes the water level further along the tube.
If the air pressure drops (usually associated with rainy weather), air pushes down less on the water surface inside the bottle and the water level in the tube will drop.

To immediately see how the water level in the tube changes, use your breath to change the air pressure inside the bottle:
Cut a straw in half and wrap more modelling clay around it, sealing to make sure that there are no air gaps.
Insert the straw into the barometer bottle mouth, and use the clay to seal over the top of the bottle and around the tubing.
Blow into the straw. If their is no air leakage, you will make the air pressure in the bottle rise, which will push the liquid up the tubing.
It takes a lot of puff to move the water line only a little. This gives a sense of the pressure changes that occur in our atmosphere regularly, but we do not notice so much (unless we have arthritis which can cause sensitivity to pressure changes in the joints).

To watch atmospheric air pressure change over time, tape the tube onto a nearby wall. Check regularly, especially when the weather is changing to see the liquid level rise or fall.
Clear weather is associated with higher pressure because local high pressure air will move outwards away from the high pressure region to lower pressure regions around. This air is replaced by air from above.
Rainy weather is associated with lower pressure because local low pressure means that surrounding higher pressure air will move inwards. Then it is forced upwards. The rising air cools and water condenses out forming clouds and often bringing rain.

Follow instructions from this activity from the Exploratorium, also attached, and summarized below:
https://www.exploratorium.edu/pie/downloads/Cardboard_Automata.pdf

In brief:
Make a frame from a cardboard box, with triangles to reinforce inside the corners. Note: do not make the frame too large, or there will be too much play and the cams won't mesh. About 20cm wide and 15cm high works well.
Stick a skewer (a "shaft") horizontally through the frame, adding a circle of foam (a "cam") to it, the placement of the hole in the cam depending on which mechanism(s) you want to make. See the attached file from the Exploratorium for ideas. It is best if the cam is at least 5cm diameter.
Add another foam cam on a vertical shaft through the top of the box that will rest on the first circle. Don't make this skewer too long or it will move sideways. A straw glued into the box to guide the skewer helps keep it upright. Washers, or modelling clay, give some weight to the cam so that it always rests on the lower cam.
Depending on where the horizontal shaft goes through its cam, the upright shaft will move round and round, or round and round and up and down.
Optional: add another circle on the horizontal shaft to make the upright shaft also go back and forth.
Decorate the upright shaft, so that the movement(s) is/are highlighted.

Students hammer nails around the edge of the board, with a curve at the top. Stretch elastic bands over to make a wall around the board.

Make the marble launcher: slide the spring onto the nail then insert the nail through the drywall anchor. Attach the launcher to the bottom corner of the board, inside the wall (right or left side, depending on the handedness of the student), using a staple. Add a blob of hot glue (or an elastic band wrapped tightly) to the end of the nail that is pulled, to stop it from leaving the shooter when it is released.

Make a channel for the marble to travel up after it is released.
Add more nails and elastic bands to the board as desired to make obstacles for the marble.
Add scoring boxes at the bottom of the board.

After students have played with their own pinball machine for a while, sit in a cirlcle to try each others:
Start with each student with their own machine in front of them, then altogether pass to the next student (all in the same direction). Students can keep their own marble to use on all the pinball machines. Keep passing until the students end up with their own machine in front of them.

See saw
Set up the see saw with the 2X6 centred on the split log.

Ask a pair of students to experiment with the see saw. They can either lift a large block (in the photo), or they can try lifting each other. (The objects are heavy, so the students should work slowly and carefully with good communication within the pair). Prompt the students to move the fulcrum and see what difference it makes.
They should find that when the fulcrum is near the load/student, they are easy to push it up in the air, but when it is far from the load, it is very hard (if not impossible).

Students can draw what they discover using standard notation:
The lever arm (plank of wood) is drawn as a straight line, and the fulcrum is a triangle under the line in the correct position. Use arrows to show where force is applied (at one end of the see saw - also called the effort), and where the resulting force is felt (under the concrete weight - also called the load).

Ask the students how the height of the ends of the see saw varies as the fulcrum is moved. They can measure the distances for more accurate recording of the results.
Less force over a greater distance (with the fulcrum near to the weight) is an easier way to lift the weight. However, in this case the weight will not move as high.
The amount of work balances: less force over a greater distance (at one end of the lever) balances more force over a smaller distance (at the other end).

Lifting a rock
Use a long 2X6 or 2X8 as a lever, and a split log as a fulcrum. If students have already experimented with fulcrum placement, ask them to tell you where the fulcrum should be placed to lift a very heavy object [it should be placed very near the rock]. With this arrangement a large rock can be lifted up a few centimetres (higher could be dangerous incase the rock slips sideways) by a child.

Optional: show photos of how people have been using levers for lifting heavy things for thousands of years.
Egyptians used long sticks as levers to move stones e.g. when making pyramids, evidenced by mortises (holes in stones placed for lever use). Try this image link:
https://krisdedecker.typepad.com/.a/6a00e0099229e8883301310fcb6a12970c-…
Indigenous North West Coast large houses are built using levers to raise the massive cedar logs. See page 113 of "Knowing Home: Braiding Indigenous Science with Western Science, Book 1". Try this link: https://greatbearrainforesttrust.org/wp-content/uploads/2018/05/Knowing…
Archimedes proved by math and geometry how a lever functions, and was quoted as saying "Give me a place to stand and I shall move the world". Try this link for a famous etching: http://www.thwink.org/sustain/glossary/images/LeveragePoint_ArchimedesL…

Lifting a marble, or small load, up high
Can also use to lift a smaller weight high with a heavier weight - see the photo of the upturned chair supporting a lever.
A pot of water is used to lift a marble up high - students were challenged to use a pot of water to lift a marble to table height.
The marble can be successfully lifted when the fulcrum is very near the bucket of water, so that the other end holding the marble can swing up high enough to reach the table top.
Review how a lever works: a lot of force at one end moving a small distance (the bucket full of water) produces a smaller force over a greater distance at the other end (hence the lighter load of the marble can be lifted high enough to reach the table top).
Relate to other levers students might be familiar with e.g. see saw.