ingridscience

Describe how Coast Salish Indigenous people, and people around the world traditionally and today, make traps in rivers to catch fish. They are a sustainable way of catching fish.
They are used seasonally, when fish are migrating up rivers, or built on mud flats to hold fish when the tide goes out.

Fish traps in rivers are placed where adult fish return upriver to spawn. Fish traps are made of rocks or woven mats, and guide the fish through a maze of walls and compartments, and since migrating fish tend to move ahead and rarely turn backward, they end up in compartments that they cannot escape from. People wade into the river and use a net or spear to catch the fish from the trap.
Fish traps are sustainable, as the fish are not damaged in the trap, and fish that are unwanted can be released back into the main river (gill nets or seines damage fish as they become wedged and lose scales).

Demonstrate the activity to students, before giving them their own materials.
The marble is a fish, and rolls around the tray, like a fish swimming in a river.
Roll the play dough into sausages and stick them to the bottom of the tray, to make shapes that will trap the rolling marble.
By forming passages with the play dough that funnel the marble to one end of the tray, but have a narrow opening which makes it hard for the marble to roll back, the model shows how fish traps work.

Either before or after the activity, show students photographs/videos of fish traps:
Photos of Squamish First Nation fish traps made from rocks on the Capilano River: https://www.flickr.com/photos/tfm/7763008392 abd https://www.cbc.ca/news/canada/british-columbia/coho-salmon-capilano-fi…
Video of a fish trap made from rocks by Alaskan Inuit, with explanation of how it is repaired and used, within a 15 minute story. https://www.youtube.com/watch?v=6li84mjUZT8
Photo of an Alaskan fish trap made from wooden stakes, with woven mats below the water line: http://wildfishconservancy.org/images/wild-fish-runs/alaskahandtrap2.jpg
Drawings and photos of a K’ómoks fish trap in the Comox valley, showing remains of the wooden poles. http://www3.sd71.bc.ca/School/abed/resources/teacher/Pages/FishTraps.as… Video and more information at https://hakaimagazine.com/features/the-ingenious-ancient-technology-con… Poles, made from Douglas Fir saplings, pounded into the sand, in a shape that direct fish into the trap. These poles remain year round. Woven panels were lashed to the poles when the trap is in use.

Cut a large lemon into three pieces, or small lemons in half, and put each piece in a little dish to contain any mess.
Cut two small slits through the skin on the top of each lemon piece, a little way apart.
In each lemon piece, push a strip of zinc (or galvanized nail) into one slit and a strip of copper (or copper-coated coin) into the other slit. These metal strips are called electrodes. The strips should be both pointing upwards but not touching each other, either in the air or in the lemon.
Attach a wire to the top of each zinc strip, and link to the copper strip in another lemon piece, forming a linear chain.
Use clothes pegs or paperclips to add the LED bulb into the circuit (and so closing the chain into a circle).

If the bulb does not light, move the strips around in the lemon a little, squish the lemons to release more juice.
The bulb will fade as the juice chemicals around each strip are used up. Move the strips to a new spot to start the electricity flow again.
Add more lemon pieces and strips into the circuit to make a higher voltage battery, which will make more current.

One lemon piece and electrodes produces 0.7 - 0.9V, so by adding more lemons and metal strips into the chain, enough voltage is generated to power the LED.

How does the lemon battery work?
Electricity is a flow of small particles, called electrons (which are part of an atom). When electrons flow through a bulb, they make it light.
The zinc pushed into the lemon starts a chemical reaction with the acid in the lemon which releases electrons. Electrons flow from the zinc strip through the wire then out of the attached copper metal strip (which also undergoes a chemical reaction with the H atoms of the lemon acid).
This current of electrons, generated by chemical reactions between the metals and the lemon acid molecules, lights the bulb.

Introduction to the activity for the teacher:
Shoes are manufactured with many different soles, depending on the function of the shoe. (For example, runners have rubberized and inundated surfaces to grip the ground, whereas tap shoes have slick metal soles to enable the dancer to click out a rhythm and slide on the dance floor.) Friction is the force that counteracts a shoe and surface sliding past each other, caused by the surfaces rubbing against each other. A flat sole or a polished floor will generally reduce the friction between shoe and floor as the flat surfaces slide past each other more easily. But friction is a complex force determined not only by the roughness of the surfaces, but also by how hard the surfaces are pushed together (for example by the weight in the shoe), the chemical material that the surfaces are made of and whether there is any fluid between the surfaces. In addition, the force of friction opposing an object starting to move (“static friction”) is different from the friction once an object is moving (“kinetic friction”). Refs 1 and 2.
Pulling different shoes across different surfaces provide a system that is easy to set up and can explore all these aspects of friction.

Review or introduce friction with students:
The force between two materials, that stops them from sliding past each other. Two surfaces that slide past each other every day are the bottom of a shoe and a floor. Tell students that they will be measuring the friction between their shoes and the surface of their desks to start, before exploring other surfaces.

Measuring friction in different shoes:
Show students how to measure the friction between a shoe and their desk, by hooking the spring scale through a strap or lace on the front of the shoe, then using it to pull the shoe along. They should pull the shoe slowly but steadily until a consistent reading is obtained. It is often easier to have one person focusing on pulling the shoe while another reads the scale.
Show students the worksheet “Friction with different shoes” (page 1 of the attached worksheet), and indicate where they will place their friction data for one shoe type with no weight, the smallest weight they have (e.g. 200g) then the larger weight (e.g. 500g), before trying a different shoe. The weight should be placed at the back of the shoe over the heel (for consistency among the groups)
Allow students to choose their shoes and take their readings, but makes sure that each group tries a cleat, tap shoe, or other shoe with a slick sole.
Students will need a circulating adult to check that they are measuring sliding friction (as the shoe is moving) and not static friction (as the shoe just starts to move), as static friction will be a lot higher and give inconsistent class results.
Once all groups have readings for at least two shoe types, ask students to graph their data on the graph paper worksheet or on the board.
Discuss results, some points to be made follow:
Students should find that for every shoe, increased weight caused an increase in the friction. Why is this? If the shoe and the surface are pressed together more firmly, the tiny bumps and indentations in the shoe and surface get caught up in each other more so increasing the friction.
Expected results and discussion:
The shoes will vary in their friction, sometimes in surprising ways. In general though, tap shoes or other slick dance shoes will have less friction, cleats will have less friction, and some (though not all) worn out runners will have less friction. Discuss these results, including comments on how flat the surfaces are (tap shoes are very hard and flat, worn out runners can be very flat) and how large the contacting surfaces are (cleats are hard plastic and only contact the table in small spots). Also discuss the materials that the shoes are made of. Some runners have soles that are rubberized, which is a tacky material which sticks to surfaces and is hence high friction.

Measuring friction on different surfaces:
Tell students that they will be measuring the friction between one shoe and several different surfaces.
Distribute different surfaces around the classroom and point out other surfaces already in the classroom e.g. carpet, cardboard sheet, a piece of foam, a layer of sand in a tray, a tray of ice, pillow.
Tell students that their group should choose one shoe and one weight, and measure the friction on different surfaces. They should start with the desk top once again, then move to different surfaces. Using the worksheet “Friction with different shoes” (page 2 of the attached worksheet), they record the friction for each surface, as well as the change in friction from the desktop in each case.
Note: as the students work, the ice tray will need to be maintained - pour off the excess water so that the shoes are moving across the ice, not a puddle of water.
Expected results and discussion:
Ask students which surfaces decreased the friction and which increased the friction, or ask them to chart their results on a common graph (see photo - note the results will likely be a little messy). As a class try and figure out possible reasons. Some are listed here:
Carpet and foam - the carpet and other knobbly surfaces have lumps and bumps which get caught up in the (sometimes tiny) bumps in the sole of the shoe and increase friction. Foam may give differing results, depending on what kind it is - although bumpy it may have a slick texture that can make surfaces slip past each other and so decrease the friction.
Sand - sand in a thin layer will likely decrease friction. This is because the individual grains can roll. Rolling is a low friction motion, as the surfaces do not slide past each other but rotate past each other. Students can relate to marbles on a floor and how their rolling motion can be hazardous if stepped upon. If the sand is deeper, the friction may increase.
Ice - if there is a very thin layer of water on the ice, the liquid will fill the bumps and grooves on the sole of the shoe, allowing it to slide over the ice more easily, hence reducing the friction. Lubricants such as oil, grease and wax work in the same way to reduce friction between moving parts of a machine or other object. With more water on ice, the friction may increase as the shoe has to push through the puddle.

Closure Discussion
Friction is a complex force that resists objects sliding past each other. We use products that have increased friction, for example to stop our shoes slipping, or to brake a bike. We also use products that have decreased friction, such as dance shoes that can slide across a floor, low-friction ice skates lubricated by the thin layer of water between the ice and skates, or oil to lubricate moving parts on a machine.

Thank you to Brenda Koch, then from Xpey’ Elementary, for teaching Ingrid how to twine.

Twining is a method of twisting strands around each other, used by BC Indigenous People, as well as many other cultures worldwide, for making ropes, fishing lines and nets, as well as for binding the thicker strands of a basket, hat or mat together.

Teach students how to twine. It is easier to start with grass, as it is stiffer and holds in place more easily than wool.
Lay two grass blades side by side and tape securely to the desk. Twist the right hand strand twice to the right (using the right hand, so that the thumb rotates over the top of the hand). Pass the right hand grass blade over the left hand blade and hold in your left hand (without letting it untwist). Twist the new right strand, then pass over the new left hand strand. Repeat down the length of the strands, not too tightly, so that the strands relax into each other to make a coil.
Optional: A twined strand can be twined again around another one, to make a stronger cord.
Twine wool with contrasting wool colours, to make a twisted pattern that can be used as a bracelet, hair piece or to hang on their backpack. The twisting motion each time is in the same direction as the twist already on the wool.

The physics in twining:
When you twist, you force the grass or wool to twist into a new position. You are putting energy into it - elastic potential energy - a stored energy in materials that are elastic and can deform. When you let go, the elastic energy is released and the wool tries to unwind again. As it is twisted around the other strand, they tighten onto each other to keep the coil in place.

Twined roots make strong fishing line or basket handles.
When strands are twined around uprights, they can make baskets or hats or other objects.
Students can try weaving in and out of small branches to mimic basket-making. Securing everything on a clip board helps.
Look at twined objects e.g. clam basket or Haida hat photos (twined so tightly it is waterproof).

Great to do this activity outdoors, near native grasses and plants that are used for twining and weaving.
At Trout Lake we found:
Willow bark (used for ropes, fishing line and nets) and willow branches for making a fish weir (they take root in the river bottom). Small flowered bullrush for basket weaving. Cedar for woven bark (clothing). Iris leaves are woven into snares strong enough to catch elk and large animals.

More information on twining used in basket weaving:
http://www.burkemuseum.org/blog/coast-salish-weaving-tools-technologies

Before the lesson:
Make frames, one per student. Use white glue to make a square from narrow popsicle sticks. Binder clip at each corner over night for a strong frame.

Introduction:
Indigenous people from BC make many kinds of baskets, often in the winter when there is more time.
An important basket is for collecting clams. It is called an open basket as it has holes in it. Clams are thrown in it with sand stuck to them. The basket is dipped in water to rinse off the sand, which is small enough to fall through the holes, while the basket catches the clams.

Make your own weaving to separate glass counters (representing clams) and gravel (the sand that clams are separated from).
Try a kind of weaving called plaiting - alternately under and over. (Kindergarteners may just need to lay across.)
Use pipe cleaners on a frame. Pour the 'clams' and sand over the weaving, to try and catch the clams on the weaving, just as a clam basket catches clams.
To reset after each test, pour the clams and sand from the tub they fell into, back into the dixie cup.
Note: clam baskets woven by the Coast Salish are more often made by twining, another weaving technique, rather than plaiting.
See the Twining activity for how to twine and a short beginner of twining around uprights (which is how clam baskets are often made).

Look at pictures of a clam basket.
Search for clam basket in the Museum of Anthropology at UBC:
http://collection-online.moa.ubc.ca/search?keywords=clam+basket
Or try these weblinks:
http://ww2.glenbow.org/search/collectionsSearch.aspx then search AA 1817 (for a picture of a beautiful clam basket, including close up images).
http://www.burkemuseum.org/research-and-collections/culture/collections… found by searching "clam basket" in the Burke Museum Ethnology Collections Database: http://www.burkemuseum.org/research-and-collections/culture/collections…
Note that these clam baskets are not made by plaiting, but by twining around the uprights.

If students have already done twining, point out the twining that holds the basket uprights together.

Open (sieve baskets) are also used for catching fish and hulling (sifting the grains from chaff).

Excellent video for post lesson: Ed Carriere (Suquamish) making a clam basket - shows gathering the cedar branches and roots, splitting them and weaving them https://vimeo.com/37561426 (15 minutes long) and article on the same process: https://hakaimagazine.com/features/the-basketmaker/

More information on basket weaving:
http://www.burkemuseum.org/blog/coast-salish-weaving-tools-technologies
From this article: "Weaving is done with only the fingers. Plaiting is done with one horizontal weft yarn passing in front and behind the vertical warp yarns. Twining is done with two horizontal weft yarns one passing in front while the other passes behind the warp. This technique can be used to create a tighter weave and allows for elaborate geometric patterns to be created."

Tell students we will be making a simplified cake to understand the chemistry underlying making a cake.

Introduction as a demonstration:
Ask students what ingredients go into a cake, and for each one write up into colums as flavourings or ingredients needed for the structure of the cake. As flour, liquids and a rising agent are mentioned, mix these ingredients into a well of a muffin tin as a simplified cake batter: about 3 Tablespoons of flour, 3 Tablespoons of water, 1 teaspoon of baking powder. (Egg and milk in a real batter are needed for binding the ingredients together as they are cooked in the oven, but are omitted in our simplified cake batter.)
As discussion continues, the simplified cake batter will rise slowly, and students will start to notice.
Ask them which ingredient made it rise [the baking powder].

Introduction as a short activity for students:
Students each get a tray and a stir stick, and flour and water are in pots with their own scoop.
Ask students to mix a little flour (about 1/4 teaspoon) and water until they make a cake batter consistency, using their stir stick to mix them together.
Then they should add a small scoop of baking powder, mix it up, then wait and watch.
Their cake batter will slowly rise, and some of them will see bubbles appearing.

Continuing:
Tell students that baking powder has three ingredients - read them from the package:
1. cornstarch
2. sodium bicarbonate, which is baking soda
3. monocalcium phosphate and/or sodium aluminum sulfate, which do the same job as cream of tartar.
Ask students to figure out which two of these ingredients mix to make gas, by mixing small scoops of them with water in wells of their tray. If they add the powders to the tray first, the water can be added to mix them together, so the scoops can remain in the pots of powders.
The attached worksheet can help students keep track of what they find.
[Remove flour and baking powder from their tables, and add baking soda, cream of tartar and cornstarch to tables.]

Students should find that baking soda and cream of tartar make bubbles, but the other combinations of two ingredients do not. (Sometimes bubbles arise from the water being squirted in, but these soon pop, and do not count as bubbles being made.) Students may get different results from each other - tell them that this happens to scientists all the time, and they should simply both repeat the experiment until they get consistent results. Sometimes a powder may contaminate a nearby well to give differing results.

Use molecular models to figure out what gas is being made as the baking soda and cream of tartar are mixed and a chemical reaction happens to make gas.
Students are given HCO3 (baking soda) and H (in the cream of tartar). Ask the to rearrange the atoms to make two new molecules. Tell them that one molecule is water (H2O) and ask them to figure out the other one, by joining all the remaining atoms and bonds and filling all the holes in the atoms. They should arrive at CO2, which is carbon dioxide, a gas.

Summarize that when cakes are made with baking powder, the baking soda and cream of tartar (or other acid) in the baking powder mix together in the wet environment of the cake batter. They chemically react to make carbon dioxide gas, which makes bubbles which are trapped within the cake batter. We can see these bubbles as holes in cake. They make the cake light and fluffy.

Test the materials to determine how rigid, elastic and malleable they are. These are the properties of rigid, elastic and malleable materials:
Rigid materials do not deform easily.
Elastic materials can be deformed, then return to their original shape.
Malleable materials can be deformed, and do not return to their original shape.
(Note that technically, I should use the term "plastic" instead of malleable. But as the word plastic is used so often in another context, it would be confusing for students. Materials with plastic properties come in different types: malleable materials can be flattened easily, and ductile materials can be drawn into a long thread easily.)

The classification of the materials will depend on their thickness and shape, for example metal can be quite rigid if it is thick, or malleable if it is thin. Any answer is fine as long as the students are manipulating the materials and thinking about how they deform.
Our results: rigid materials were marble, rock, hard ball, bow tie pasta (spaghetti would be elastic too). Between rigid and elastic were metal strip, popsicle stick, plastic spoon, bouncy ball. Elastic materials were balloon, foam sponge. Between elastic and malleable were styrofoam and pipe cleaner. Malleable materials were play dough and tin foil. Between malleable and rigid is ping pong ball (though nearer rigid than on the photo).

If students are given several types of balls, ask them to see how elastic or rigid they feel, then based on that, predict how high they will bounce. The more elastic balls will generally bounce higher than more rigid balls. The elastic material stores energy as it is deformed, which is released again as it returns to its original shape, giving the ball energy to go higher.

At a molecular level, some of these properties can be explained.
Elastic materials are often made of long molecules that can bend and stretch, then return to their original shape e.g rubber. Elasticity may also be due to air pockets in the material that can be compressed e.g. foam.
Rigid materials will be made up of tightly-bonded molecules that are hard to move past each other. Sometimes rigid materials are brittle, so that with enough stress they break apart suddenly as the bonds are
Malleable silly putty has many weak bonds between long molecules that can be broken, then remade in new positions.