ingridscience

Ask students to place one hand in the cold water and one hand in the very warm water, and leave them there for at least one minute.
Then place both hands in the medium temperature water. What temperature does each hand feel? (I found it easier to place one hand at a time in the medium temperature water, as the different sensations coming from each hand make it hard for the brain to process what is going on in each hand.)

Students should find that the hand that was in the cold water will feel warm, and the hand that was in the warm water feels cold.
The temperature receptors, called "thermoreceptors" in your hand detect temperature changes, and signal that change to your brain. After a while in water of one temperature, they get used to that temperature, and on being immersed in a different temperature signal the relative change in temperature. Hence the colder hand feels warmer, and the warmer hand feels colder, even thought they are both immersed in the same temperature.

Here is more detail on the receptors that detect temperature:
We have both cold thermoreceptors that are activated by cold, and warm thermoreceptors that are activated by heat. Cold receptors fire more signals when they are cooled, and decrease the signals sent during warming. Warm receptors increase signal rate when they feel warmth and decreased signal rate on cooling. But, in addition, either thermoreceptor, when exposed to the same temperature for a while, will tire and stop sending signals about the temperature. Hence the hand that gets used to cold has cold receptors that are tired, so when it enters the medium water only the warm receptors will fire. By contrast, in the hand that gets used to warm, the warm receptors have become tired, and when the hand enters the medium water only the cold receptors will fire. Hence different signals are sent about the same temperature water.

Test seawater for pH (it is generally pH 8 or basic).
Compare to drinking water (neutral or slightly acidic/basic).
Compare to stream water, pond water and fish tank water (usually neutral).
Students might also want to test the pH of their spit (neutral).

Water chemistry varies with the kind of rock that the water flows over/through, and the chemicals that are added during treatment.

Ocean water becomes more acidic as more carbon dioxide dissolves in it, which happens as the atmospheric carbon dioxide goes up.

Vancouver drinking water is from North Vancouver watersheds, and is naturally slightly acidic. The treatment process makes it a little higher pH.

From Metro Vancovuer website 2021:
Metro Vancouver currently delivers water with a pH of 7.7.
Adjusting the pH is an existing key component of Metro Vancouver’s water treatment process because our untreated source water is naturally slightly acidic. Increasing the pH to a target range of 8.3 to 8.5 will:
• Reduce the release of copper from pipes in buildings caused by low pH in the region’s water;
• Reduce leaks in pipes caused by copper corrosion;
• Help preserve the lifespan of pipes and hot water tanks; and
• Reduce green stains on tubs, sinks, and grout.

Sorting feathers:
Feathers can be sorted into types. The wing and tail feathers are long. The tail feathers have the hard tube or 'rachis' up the middle. On wing feathers the rachis is to one side. Both of these kind of feathers are used to push air and help the bird fly and change direction.
Body feathers have fluffy barbs at the bottom of the feather which are for trapping air and insulating the bird.

See these images for feather types: https://www.birdsoutsidemywindow.org/2019/12/17/how-to-identify-feather… (second image) or https://academy.allaboutbirds.org/wp-content/uploads/Bird_Biology-feath… (from https://academy.allaboutbirds.org/feathers-article/)
See these images for which feathers are on which parts of a bird: https://www.researchgate.net/figure/Structures-morphotypes-and-body-pos…

Looking at feather structure:
On a long wing or tail feather, gently pull the barbs (the hairs coming off the shaft), until they pull apart, then stroke them back together again.
The barbs have little hooks (called barbules) that zip together and keep the feather in a flat plane. The flat plane can push air and help the bird fly and change direction.
Look closely at feathers under the magnifier and microscope. Find the interlocking barbules along the barbs.
Feather structure diagram: https://www.britannica.com/science/feather

Fluffy downy feathers do not have barbules. Their barbs float apart and form air pockets that are excellent for insulation.

When birds preen, they pull their feathers through their beak to zip barbs together again.
They also add oil, so that the feathers are waterproof.

Light the paper and drop it into the bottle.
As it goes out place the egg on the top of the bottle.

As the air in the bottle cools again and contracts, the low pressure in the bottle pulls the egg into it.

Prepare the rocket by drilling through the cork.

Add water to the rocket, insert the cork containing the needle attached to the pump.
Put it in the stand/stand upright.
Ask everyone to stand well back, as it will take off with no warning at high speed.
Pump air into the rocket until it takes off.

The pressure of air in the bottle above the water increases until it is too high to be held in by the cork.
As the cork flies out, the water flies out too, helping project the rocket higher.

Experiment with amount of water for the best flight.
Too much water means there is too much weight. Too little means there is not so much water shooting out to project the rocket higher.

Lots of great explanation, plus how to construct on the Naked Scientists website: http://www.thenakedscientists.com/HTML/experiments/exp/water-rockets/

Add a little ethanol to the jug.
Swirl it around to coat the sides and evaporate into the volume of the flask.
Ignite at the top.

Discuss the chemistry of the reaction:
ethanol + oxygen -> water and CO2
Model the chemistry of the combustion reaction

Light the ping pong ball and watch it burn.

The ping pong ball is fuel for a combustion reaction: it combines with oxygen to release heat and light. Carbon dioxide and water are made, along with an ash.

Once the combustion reaction starts, the heat it generates keeps the reaction going.