ingridscience

Walk students to the middle of a strip of stores.
Then blindfold one of them, spin them around so that they do not know which direction they are facing in, then ask the other students to lead them into a store that they are familiar with. (Teach the leaders how to allow the blind student lead, rather than pulling them along at a pace that is not comfortable.)
Ask the blindfolded student to state what they smell, hear, touch etc, until they can name the store they are in.
If the student guesses where they are quickly, they can be given the extra challenge of finding a specific location or product in the store.

(Ideas for stores with good smells: pizza place, herb/aromatics shop, coffee shop, plant store, pet store.)

Once the blindfold is off, discuss how our other senses become heightened to compensate for the loss of sight.

Discuss how other animals use their senses of smell and hearing more than humans do.

Discuss how blind people must navigate with their other senses.
Some interesting facts about how blind people sense their surroundings:
Some blind people use echolocation, by clicking their tongues and listening for the echo back to find out where objects are (just like bats or marine animals). Some blind people can so precisely tell where objects are using echolocation that they can use this method for mountain biking or basketball. (Experts in blind echolocation can even listen to a recording of tongue clicks echoing, and state what objects were there when the recording was made!) https://www.youtube.com/watch?v=WHYCs8xtzUI
Brain scans (with functional MRI technology) of blind people using other senses (touch, sound) show that the information from these other senses goes to their visual cortex (just like the visual information in a sighed person). So their brains constructs a visual map of what they "see" using their other senses.

Allow students to try out the devices, and either have them try and figure out how they make heat themselves, or discuss as a group.

The space heater, hair dryer, kettle and incandescent light bulb make heat from electricity:
The electrical energy is converted to heat energy by the device, by running a current through a metal coil or plate to heat it up.
In the space heater and hair dryer, the hot metal warms air, then the hot air is blown out with a fan.
The metal in the kettle heats the water above it.
The incandescent light bulb is designed to produce light, and works when electricity passes through a thin wire inside the bulb. The wire heats up an emits light, but also a lot of heat. Incandescent bulbs are not efficient for their purpose as only 5% of the energy emitted is as light - the rest is heat, hence the the conversion to other kinds of light bulbs (fluorescent, now LED).

The candle and hand warmer make heat from chemistry:
The candle gives off heat as the wax burns (a chemical reaction - see candle chemistry activity. A candle is used for light, and also for heat sometimes.
The hand warmer works as sodium acetate crystallizes (turns from a liquid solution to a solid). It is in solution until the metal disc is bent, which initiates the crystallization. You can then see the crystal formation spreading out from the metal disc. Crystallization of this chemical produces heat. (You can reset the hand warmer by heating it up to dissolve the sodium acetate in the water again.) Hence chemical energy is converted to heat energy in these hand warmers.

Other discussion points:
Our bodies make heat from chemical energy.
Rubbing your hands together makes heat from friction.
We heat our homes by burning gas (a chemical reaction that makes heat, similar to the candle), or from electricity (heating up metal inside a device, similar to the space heater and hair dryer).
Geothermal energy is a newer, environmentally sound way of heating buildings - heat is extracted from deep underground and used to directly heat buildings, or used to heat up water that can be used for heating. Thousands of buildings in Richmond, BC are heated in this way.

Logic puzzle to figure out what molecules can make foam
Beforehand, make up dropper bottles of six liquids: water, distilled water, drink mix, soap, skim milk and whole milk (make sure the milks are cold).
Students drip each liquid separately into a tube to fill it half way.
Cap and shake hard.
Look for foam above the liquid i.e. bubbles that remain for more than a couple of seconds. (Make sure the milks are really cold, when they will make foam. The soap will also make foam. The waters and the drink mix should not make foam.)
Figure out which molecules make foam from the liquids that do and don't make foam. This puzzle is most easily done by figuring out which molecules do not make foam, and then deducing which ones must be making foam in the liquids that do foam. Use the attached foam test worksheet to help.

Testing molecules to see which ones make the foam in a recipe or environment
Beforehand, make up dropper bottles of the molecules that are in the recipe or environment:
To find out what makes the foam in meringue make bottles of water, protein (in the egg white), sugar and salt (the cream of tartar).
To find out what makes the foam in milkshake make bottles of water, protein, sugar, salt and fatty acid (all components of milk).
To find out what makes the foam in ocean waves breaking on a beach, make bottles of water, salt, protein (from living things in the ocean) and fatty acids (from living things in the ocean).

In these activities, protein and fatty acids will make foam, but water, salt and sugar will not.

How is the foam made?
Before the tube was shaken, the protein/fatty acid molecules were spread out. During shaking, air bubbles are mixed in. The protein or fatty acid molecules cluster around these air bubbles, holding them in place. The foam you see is hundreds of tiny air bubbles held in place.

More detail: the protein/fatty acid molecules have two different parts - one end of the molecule likes to be in water ("hydrophilic") and the other end does not like to be in water ("hydrophobic"). The hydrophobic parts stick into the air bubbles (so only touch air) and the hydrophilic parts project into the water surrounding the bubbles. The protein/fatty acid molecules surrounding each air bubble stabilizes them so that they remain suspended in the mixture.
Salt/sugar molecules don't cluster around air bubbles, so they don't make foam.

A foam is a kind of mixture called a colloid, with a gas suspended in a liquid. (See the attached mixtures summary for more information on mixtures.)

The attached ocean foam activity booklet is a self-guided activity investigating the molecules that make the foam in the ocean.

Please note that in a class of students it is likely that one of them is at least partially colourblind (1 in 12 males are colourblind). As this is an activity distinguishing colours, these students will not be able to tell some colours apart and perceive some colours differently, although the activity will be no less interesting for them. The common red/green colour blindness means reds and greens (or colours containing reds and greens such as browns) look similar. More information at colourblindawareness.org and colorblindguide.com/post/the-advantage-of-being-colorblind.

One of the fall leaf colours is in leaves all year but is hidden until the fall. Do an experiment to find out which fall colour is hidden in green leaves.

Cut a strip of filter paper about 1cm wide and about as tall as the tube (I make strips 12cm long for my 50ml "Falcon tube" pictured).
Cut a strip of spinach leaf, 1-2mm wide, and tape across the filter paper strip near one end (about 2cm in).
Use a coin to roll over the spinach leaf to transfer the colour from the leaf to the filter paper. (Leave the tape on when you are done, as it might rip the paper if you try and tear it off.)
Fold/roll the end of the filter paper over/around the toothpick, and hang it in the empty tube. Adjust the height so that the bottom of the filter paper hangs about 1cm above the bottom of the tube, and the green pigment is about 3cm from the bottom of the tube. Remove the filter paper and toothpick again.
Add rubbing alcohol to the tube to a height of about 2cm, then hang the filter paper back in the tube, making sure that the green pigment is not submerged, but the end of the filter paper strip is submerged. If it looks like the colour will dip into the liquid, fold/roll the filter paper a little higher. Also make sure that the filter paper is not touching the sides of the tube.

Allow the chromatogram to run. Almost immediately the colours will start to move up the filter paper, but the further up it moves, the more dramatic the separation of the colours will be. I suggest a minimum running time of 10 minutes; 20 minutes or more is ideal, as in the photo.
Note that in a class of students the results will be very variable, depending on how tidy their chromatogram assembly is; however almost all students should see some yellow separating from the green. (Using 70% isopropyl alcohol, the colours move more slowly and are not separated as well with 95% ethanol, so in this case a minimum would be 30 minutes. I have not tried 99% isopropyl alcohol but would guess that it is more like the 95% ethanol.)
To see the colours more clearly while the chromatogram dries, lay on a white paper towel or other white paper.

The leaf pigment molecules are soluble in alcohol and are carried along by it, but they also get caught up on the surface of the filter paper, before moving along again. Each molecule interacts with the filter paper and the alcohol a little differently (as the molecules have different shapes and charges), so they move at slightly different rates up the filter paper. The molecules become separated from each other more and more clearly as the chromatography proceeds.

In spinach leaves, a bright yellow colour separates out from the green.
The yellow is a pigment molecule (called xanthophyll) which moves ahead of the green chlorophyll molecules.
If you try other leaf colours, you will see their colours separate out too. Green leaves only have green and yellow pigment in them. Red leaves may also have yellow pigment in them. Yellow leaves only have yellow pigment in them. Therefore yellow pigment can be masked by the green or red pigments, so is only visible when neither are present.

Relate to fall leaf colours:
The yellow pigment molecules are always in leaves, and help with photosynthesis, but their colour is usually masked by the green chlorophyll. In the fall, the green chlorophyll molecules break down as the leaves die in preparation for winter. As the green molecules disappear, the yellow molecules become visible.
Red and brown pigments are not in leaves before the fall, but made as leaves break apart sugar molecules in preparation for winter. The red molecules appear around the same time that the green molecules disappear.

Lay the cheesecloth over one of the cups.
Secure with an elastic band near the rim of the cup.
Use the other cup to gently push down on the centre of the cheesecloth, while using the other hand to roll the elastic band down a little, to make a well in the cheesecloth.
Add 1 teaspoon vinegar to the other cup.
Heat the milk in the microwave until very warm (can be done in bulk and while students are preparing cups).
Add 1/4 cup warm milk to the vinegar in the cup.
Let sit for a minute for the solid "curds" to form.
The watery liquid that separates out from the curds is called "whey".

Protein molecules (specifically casein) in milk mix with the loose hydrogen atoms in the vinegar (an acid) and a chemical reaction happens, making solid "curds". Heating the milk helps the reaction.
(For older students: the casein molecules in the milk have a negative charge. The loose hydrogen atoms in the acid have a positive charge. Opposite charges attract, so the casein molecules and loose hydrogen atoms group together to make the curds.)

Pour the curds and whey mixture into the cheesecloth on the cup, so that the curds are trapped in the cheesecloth and the whey drains into the cup below.
Pour 1/4 cup of drinking water over the curds to rinse the extra acid off.
Press the curds with the spoon, to drain any last liquid, then scoop out onto a plate.
Add a sprinkle of salt and mix in, before eating on a cracker. It is a great snack food.

Compare taste and ingredients with a commercially-produced cottage cheese.
The cottage cheese ingredients will include some kind of milk, as well as a bacterial culture (e.g. Lactobacillus) which does the same job as the vinegar (see notes below), and likely ingredients that make it more goopy (e.g. guar gum, carrageenen), and possibly some kind of preservative (e.g. potassium sorbate).

Notes on commercial cheesemaking:
Queso blanco (common cheese in Central and South America) is made in the same way as this activity, by adding an acid such as vinegar to warm milk.
Another methods for making a simple cheese use a bacteria (e.g. lactobacillus) instead of adding acid directly. As the bacteria grows it slowly releases an acid (lactic acid), which forms the curds. (Lactobacillus, naturally present in milk, can be used, and/or more lactic acid bacteria can be added.) Cottage cheese is made in this way. (Ricotta cheese is made from whey.)
Rennet is also used to help curd formation by many cheese-makers. It cleaves a piece from casein molecules, which, like the hydrogen ions, cause them to clump together.
Mature cheeses (which take longer to make than simple/quick cheeses) have other bacteria and mould cultures added to give the cheese more flavour and to change the texture. e.g. swiss cheese uses lactobacillus to form the curds, then other bacteria to remove the lactic acid to add other flavours and to make the holes.
https://www.uoguelph.ca/foodscience/book-page/cheese-making-technology-…

Notes on spoiled milk:
When milk is pasteurized most bacteria is killed, including harmful pathogens E.coli and Salmonella. However some spores and some kinds of bacteria survive e.g. lactobacilli. Milk "spoiling" i.e. forming curds when it gets old, is due to the lactobacillus bacteria growing and producing acid. Although lactobacillus is harmless, spoiled milk may also contain harmful bacteria which have grown from spores, so should not be drunk.

See the attached cheese booklet, for an inedible version of this activity run as a stand alone in a science museum (the curds are separated in a centrifuge for speed).

Bees can talk to each other with smelly molecules, called pheromones.

Students squeeze and sniff each of the bottles. Ask them what the smell makes them think of. (Likely lemon, banana, cheese and nothing.)

When a bee smells these same molecules it thinks of something quite different. Students match the molecule labels on each bottle with the molecules on the sheet to find out what each of these molecules means to a bee:
This might smell like bananas to you (banana smell), but to a bee it means war. This molecule signals bees to attack an intruder.
This molecule says it's moving day to a bee (lemon smell). Bees smelling this molecule swarm and move to a new hive
Feel alarmed when you smell this? A bee would (cheesy smell). Guard bees release this molecule to call for help when there is an intruder.
Although we humans can't smell this molecule (oxodecanoic acid, so use empty bottle), it is a perfume for bees. Queen bees release this molecule to attract males.

It may seem strange that other animals communicate with smell molecules. We mostly use our other senses to communicate.
Many creatures communicate with smell molecules.Dogs use smell molecules to mark territories. Ants leave pheromone molecules for each other to show the way to food.

Put 10 drops of fake stomach juice into each of two cups. Stomach juice contains loose hydrogen atoms.
Add a drop of dye to both cups of fake stomach juice. The color of the dye shows you the number of loose hydrogen atoms in the stomach juice.
How many hydrogen atoms are there in stomach juice?

Real stomach juice, like the fake stomach juice in your experiment, has lots of loose hydrogen atoms in it. Your stomach uses the loose hydrogen atoms to digest food. But sometimes stomach juice spills into the tube above the stomach. Hydrogen atoms are not meant to be in the tube above the stomach, and cause a burning feeling. This pain is called heartburn. When we get heartburn, we take an antacid.

Take a small piece of antacid and grind into a powder with the mortar and pestle. Dip a wooden stick into one of your cups of stomach juice to make it wet. Pick up some of the antacid powder with the wet stick. You only need a small amount.

Mix the antacid powder into one of your cups of stomach juice and dye. Leave the other cup alone. Keep mixing until the stomach juice changes color. Be patient — it may take a minute. Compare your two cups. What did the antacid do to the number of hydrogen atoms in the stomach juice? (Look at what colour the dye turned and infer what has happened to the number of hydrogen atoms).

How did the antacid take away the hydrogen atoms?
The antacid contains carbonate molecules. Find carbonate in the active ingredients on the antacid bottle. The carbonate molecules capture the loose hydrogen atoms to make a different molecule. (Students can build the molecules to see the reaction: CO3 + 2H -> CO(OH)2

How do antacids get rid of heartburn?
Just like in your experiment, the carbonate molecules in the antacid capture the loose hydrogen atoms in your stomach tube and the burning pain of heartburn goes away.
antacid = "anti-acid": Antacids get their name because they remove (or neutralize) acid, which is the same as removing hydrogen atoms.