ingridscience

Explain that inside the plastic of the light stick is a glass rod. One chemical is inside the glass rod and another is outside. When you snap the glass rod by bending the light stick, the chemicals mix together, and the chemical reaction produces a new molecule that glows.
Turn the lights out, then ask students to snap their sticks all together. Ask students to look closely as the chemicals mix - they should be able to see a swirl of colour as the chemicals react and new coloured glowing molecules are made.
First photo shows the chemicals mixing and making light.
(Older students: the tube contains hydrogen peroxide, which mixes with a chemical outside the tube. Two chemical reactions result in the dye getting excited as it gains energy. It releases this energy again as light. Additional dyes make the glow sticks different colours. See Wikipedia entry for more details).

Ask students to find out how heat and cold affect the rate of the chemical reaction in their light sticks, by dipping the light sticks in the warm and iced water tubs.
They should have found that in the warm water the light stick glows more intensely. This is because the heat energy causes the molecules in the light stick to move around faster, hence collide more often and chemically react to make more glowing molecules.
The light stick dipped in cold water should become dim. Heat energy leaves the lights stick and moves into the cold water, hence the molecules in the light stick have less energy and move around less. The cooler molecules collide less frequently, so undergo fewer chemical reactions to make glowing molecules.
(Sometimes students see something different, possibly due to the intensity of the glow stick affecting the sensitivity of our eyes in the darkness. These are real results as they are what the students found, but during discussion focus on what the majority of the students found.)

Students can make bright and dark stripes along their glowstick by dipping in one tub, then dipping it not as far into the second tub.

Discuss how the chemicals are used up when it glows brighter, and how they can preserve their glow sticks by putting them in the freezer overnight to slow the chemical reaction down.

Students can draw the candle while it is burning, to notice the different colours of the flame, the liquid wax below the wick etc.

State changes in the wax:
Solid to liquid to gas. The solid wax melts with the heat of the flame, and the wick draws the liquid wax up by capillary action. Once the wax is a gas it can burn.

Energy transformations with a candle:
Chemical energy of the candle wax is converted to light energy and heat energy.

Chemical reaction of a burning candle:
Place a jam jar over the candle - it burns for a while then goes out.
The wax needs oxygen from the air to burn. Also note that water condensation builds up on the inside of the glass.
Place differently-sized jars over identical burning candles, to see that the candle with the larger jar will burn longer (as there is more air in it).

The molecules in the candle wax and oxygen from the air combine and rearrange, and release heat and light as they do so.
Optional: use molecule models to show a simple version of the chemical reaction: CH4 + 2O2 → CO2 + 2H2O. Called combustion. The reaction product water is visible on the glass.
(Paraffin wax is actually longer chains of C and H atoms, called alkanes, with average 25 carbons. So the chemical reaction would be C25H52 + 38 O2 → 25 CO2 + 26 H2O. The generic chemical formula of wax is: C(n) H(2n+2). The wax combines with more molecules of O2, to release the same products.)
Cover identical candles with differently-sized jars at the same time. Ask students to predict which one uses up oxygen first. (Students need to estimate the relative volumes of the jars.)

Candle trick:
Once the flame of a larger candle has been lit, it can be blown out, then relit from a height above the wick. The wax vapour still in the air ignites, which then relights the wick. The flame must be quite big for this to work.

Additional information on flames:
The flame is a mixture of hot gases, primarily CO2, water vapour, oxygen and nitrogen.
The yellow colour of the flame is due to soot particles glowing because they are hot (black body radiation). Other colours in the flame are from transient reaction intermediates during combustion such as the Methylidyne radical (CH) and Diatomic carbon (C2). These molecules are excited, then emit blue and green visible light (spectral band emission).
https://en.wikipedia.org/wiki/Flame
Try burning copper sulphate or other chemicals to make other flame colours.

For more detailed chemistry of a candle burning see the ChemMatters issue on candle chemistry: http://chicagoacs.net/statefair/CD-2008/Chemmatters/2007_12_smpissue.pdf

Add a couple of drops of indicator dye to the water in the cup to measure the pH of the water. It should be around 7.
Add some carbon dioxide to the water from breath: either blow through a straw into the water, or blow into the tube and then shake the exhaled air into the water (repeat blowing into the tube and shaking as necessary), until the colour changes.
Read the new colour of the water on the pH chart - it will have dropped i.e. become more acidic, to about pH 6.

The acidification of the water is reversible: waft in fresh air and shake it into the water. This air has less CO2 than our breath, and slowly, as more air is wafted into the tube and shaken into the water, the pH of the water will return to neutral. It will take longer than acidifying the water in the first place.

Climate change and ocean acidification
The water in the tube absorbs the CO2 from your breath, just as the oceans absorb increased CO2 in the Earth's atmosphere. As the CO2 in the water increases, the pH of the water falls - it becomes more acidic.
As we increase the amount of CO2 in our atmosphere through emissions, we are acidifying our oceans.

Ocean has changed by 0.1pH unit, which is a 30% increase, since the industrial era.
Lakes are more variable because of the rock type they are in, but they are also becoming more acidic.
Many chemical reactions, including those that are essential for life, are sensitive to small pH changes. (In humans: blood pH must be 7.35 - 7.45. Blood pH drop of 0.2-0.3 causes seizures, comas even death.) A small change in seawater pH affects marine life, especially marine life with shells: corals, mussels, clams, oysters, urchins, zooplankton (tiny drifting animals). Their shells become fragile and they die.
A tiny change in acidity has a profound effect on ocean life, and so food chains.
See website: https://ocean.si.edu/ocean-life/invertebrates/ocean-acidification#:~:te….
Luckily ocean acidification is reversible. So if we can reduce the CO2 in the air the ocean water pH will rise again.

A dramatic climate change and ocean acidification event happened during Earth's history, and is evident in ocean bed core samples.
The Paleocene-Eocene Thermal Maxiumum (PETM) was a major greenhouse warming event 55 million years ago, resulting from a massive carbon release into the atmosphere (likely methane as well as CO2) which acidified the oceans. Ocean bed core samples show that this increase in greenhouse gases led to a sudden decrease in shell deposits (e.g. https://www.ecord.org/website/wp-content/uploads/2016/02/replica208a.jpg Also image here or here) - the shells of ocean animals dissolved in the more acidic ocean water before reaching the ocean floor, and the core samples showed just red clay. The greenhouse gases we are currently releasing into the atmosphere are at a much greater rate than this previous greenhouse event, and will lead to a similar effect on ocean life. Life in the oceans is linked to all life on Earth, so if we affect ocean life by acidifying ocean water, there will be knock on effects to all life on Earth.
But, there is hope!
As the students waft fresh air into their tubes, the acidification of the water will reverse and it will return to pH 7.
This shows that ocean acidification is reversible. If we can lower our emissions to reduce the CO2 in the atmosphere, the oceans will recover.

Blood CO2 levels affect our brain and heart response
When you exert yourself you need more oxygen. You also release more CO2, which makes your blood more acidic. A part of the brain called the medulla oblongata measures the pH of the blood, so can determine how much CO2 is in the blood. Once the acidity gets to a certain level, the medulla oblongata signals your body to speed up breathing and to increase heart rate. Increased heart rate will increase O2 levels in the blood again and also remove the excess CO2 from the blood.
(You can use the cortex of your brain to override and slow down breathing by thinking about it.)

This activity is how to dissect the brain before a lesson.
Follow the description of the parts of the brain, and associated activities, in the brain lesson.

The brain will probably already be cut, with left and right sides separated.
If not, slice it in half.
Look at the parts: cortex, cerebellum, mid and hind brain, corpus callosum: see labelled image at www.biologycorner.com/anatomy/sheepbrain/brain_dissect07.jpg

Discuss the functions of the parts:
cortex: thinking, reasoning, also optic, motor and olfactory areas.
cerebellum: fine motor control
mid and hind brain: basic processes such as breathing, heart rate, sleeping, waking etc
(See the Nervous System lesson plan for more details)

The intact brain can be stored in the fridge for days if covered in saran wrap to prevent drying out.

To see more cut the brain with a sharp penknife.
Cut parallel to the cut already made separating the left and right halves, but more lateral, to reveal the striatum and possibly the hippocampus.
Cut through part of the cortex to show the white and grey matter (the myelinated axons and the pinkish cell bodies).

Great images of a sheep brain dissection at:
https://www.biologycorner.com/anatomy/sheepbrain/
More nice photos at:
www.exploratorium.edu/memory/braindissection

Rocks may be made up of one mineral, or a group of minerals whose crystals have grown together. To help identify a rock by the minerals in it, there are a variety of tests including test for hardness and streak colour.
1. Testing for hardness:
The Moh’s scale is a scale of relative minerals hardness from 1 (talc; very soft) to 10 (diamond; very hard). It is used to help categorise and identify minerals. The hardness of a mineral can be measured by how easily it is scratched, either by other minerals of known hardness or with calibrated tools.
Students use a steel butter knife blade (scratched by minerals more than 5 or 6) to test the hardness of minerals to help identify them (see attached example). Other common materials to test for hardness are: fingernail (2.5), copper penny (3-3.5), steel nail (5) , pocket knife (5.5), window glass (6), steel file (6.5).
2. Testing for streak colour:
The overall colour of a mineral may vary if it contains impurities or has an irregular crystal structure, whereas the powder of a mineral has a more consistent colour. Scraping a mineral across a “streak plate” (unglazed porcelain) produces a line of powdered mineral whose colour can help identify the mineral. (If the mineral is harder than the streak plate (~7 on Mohs’ scale) another crushing method must be used.)
Scrape the minerals across the porcelain to examine their streak colours and identify them (see attached example).

These tests can be used to investigate locally mined minerals and their products e.g. bornite is mined in BC for its copper content (native copper sources are rarer). Much copper is recycled.

Go on a beach walk to find granite, or bring it into the classroom. Students will have seen it frequently, but likely not have taken notice.
On Vancouver beaches, granite (an igneous rock made up of different minerals) is often in the form granodiorite (black granite), which is speckled black, white, and grey/pink. Other common Vancouver beach rocks: smooth black rocks are likely to be basalt (igneous rock, cooled lava), and flat rough light brown rocks are likely to be sandstone (sedimentary rock made up of different minerals). Smaller pieces of quartz (a mineral) may also be found - clear or yellowish and more shiny.

Younger students can sort granite from other rocks by its speckled appearance.
Students can draw the outline of their black granite, then choose one part of it to draw in detail. (A pencil is sufficient to show the blacks, greys and whites).

There are three minerals in black granite: mica, quartz and feldspar. They make up the patches of colour in the granite.
Ask students to name the colours they find, using their flashlights (and optionally magnifiers with older students, but note that rock will scratch any kind of magnifier). Then write up the colours, assembling them into the minerals they are likely to be:
black, gold, silver (mica)
white, grey-blue, purplish (quartz)
yellow, orange, pink, brown (feldspar)
Name the minerals for the students.

As they look further at their rocks, and try and find the largest crystals they can (the largest "grain size'), circulate with samples of black mica, quartz and feldspar. Students can shine their flashlights on the samples you bring to see their colour and shiny surfaces better.
Alternatively, display the minerals for the students to look at independently at a station (see photo).

More information on the minerals in granite:
Another form of mica is white.
Quartz can come in other colours and makes beautiful crystals - show amethyst if available.

(Optional: show other rocks where the minerals are distinguishable).

Discuss how the black granite was made.
The black granite we are holding was once deep inside the earth. It is so hot in there that the rocks have melted (called magma) and all the minerals are liquid (show picture of a cross section of the earth). Imagine how hot it needs to be to melt rocks! As magma slowly moves towards the surface again it cools down, and this granite was made when mica, feldspar and quartz organized into their individual crystals as they cooled.
Some magma comes to the surface fast, and erupts from volcanoes. Magma from volcanoes cools very fast to form igneous rock, but it has much smaller crystal grain sizes than igneous rock that cooled inside the earth. Show volcano rocks - basalt (common here), pumice and obsidian. Can see gas bubbles in them.