ingridscience

Before the lesson if using sticky Q-tips:
Dip the cotton tips of the Q tips in rubber cement, then leave to dry (turning frequently to start if glue drips downwards).
Paint rubber cement on the wide popsicle stick.
Package in baggies 30 Q tips and one wide popsicle stick per group.

For either method:
Ask students to make a structure that is made up of triangles. The structure could be high or wide.
If part of a bridges lesson, ask students to make the start of a bridge, with Q-tips building up from the popsicle stick and curving up and over. The challenge is to build a structure that is self supporting, as real bridge structures are (they do not hang on themselves, but are solid at every stage).
Tell students, based on previous discussions, or when they need assistance, that triangles are strong shapes that will support themselves, and so the should include many triangles in their structure.

Show the students how a ring and pin game can be made from a ring of bone (e.g. slice of leg bone) and a rib.
Demonstrate playing the game, the goal to try and catch the ring on the pin.

Give students a selection of ring and pin games made from skewers, chopsticks and rings (or they can make their own).
The string needs to be light, so that its weight does not drag the ring about, making it harder to catch on the pin.

The smaller rings can be quite hard, so make sure to test out first.

This game, as well as being made from bones, is found world-wide, made from many different materials.

Ring and pin game from Niwasa Kendaaswin Teg, a not for profit charitable Indigenous organization: https://www.youtube.com/watch?v=DxAOjJ9YZVM. Information on traditional materials used, and ideas for your own materials.

Show students how to set up their bar, spanning it between two desks, or chairs, and taping to stop it moving around.
Using a large binder clip, hang the pulley from the bar. Or they can attach their pulleys elsewhere in the classroom using the large binder clip. Show them how to thread the string through a pulley and add a cup to each end of it using the small binder clip, then add counters.

Ask them to experiment freely with the pulleys. Give them ideas if they need them, writing them on the board to get them started, and adding as students find new ways to use them.
The youngest students I would help them set up one string over one pulley, then ask them to move the cups up and down with counters. They can be challenged to raise a flag, given some paper to tape or clip to one of the strings.
Older students can be challenged to raise a cup of counters both fast and slowly, balance two cups either side of a pulley, drag an object over their desk using counters in a cup and a pulley, or make a zipline. A clever system can be set up by hanging weights below a pulley which sits on top of a line.

Discussion with what they discovered should include how pulleys change the direction of a force. Counters in a cup or pulling down on a string in one direction moves an object in the opposite, or another, direction.
Show images of simple fixed pulleys that change the direction of a force on a flagpole.

Discussion around how objects can be balanced in two cups either side of a pulley, or one cup can be moved up slowly, can lead to how an elevator works. An elevator is a heavy car which the people go it, with a counterbalance on the other side of the pulleys. Elevator with counterweight visible here. As both these items are heavy, and nearly balanced on each side of a pulley, it does not take much force from the motor to move the car up and down (while the counterbalance moves in the opposite direction).

Students may notice, or can be asked to compare how many counters are needed to lift an object when the string goes through the pulley, or simply loops over the bar. This demonstrates how pulleys reduce friction by turning when the string moves over them. Without a pulley, it takes more forces to pull the string.

Before the class, tape hooks to the edges of desks.

Discuss stretchiness as a property of a materials, and tell students they will compare how stretchy different elastic bands are.
Demonstrate how to hang an elastic band from a hook, then hang the weight on the band.
Measure the length of the stretched elastic band, making sure the zero of the ruler/measuring tape is at the top of the band, while reading off the number at the bottom of the band.
Students measure the stretchiness of different bands.
Then they can try doubling up the bands and looping them together to measure their combined stretchiness.

At the molecular level, stretchy materials have molecules that are curled up and coiled. When the materials is stretched, they uncoil and straighten out, but when released return to their coiled form.

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 (and photo above)
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. 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.
http://www3.sd71.bc.ca/School/abed/resources/teacher/Pages/FishTraps.as…
https://hakaimagazine.com/wp-content/uploads/shapes2-fish-trap-people.p…
Video and more information at https://hakaimagazine.com/features/the-ingenious-ancient-technology-con…

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.