ingridscience

Demonstrate to students the parts of the lever and how to set it up:
The paint stirrer/ruler is the lever arm; the pencil/dowel is the fulcrum (the pivot point).
Balance the lever arm on the fulcrum, so that it can tip back and forth like a see saw.
Make a ball to of foil, place it on one end of the lever, then push down on the other end of the lever to project the foil ball upwards.

After students have played for a while, ask students to start taking measurements. They should make sure they can exert the same force on the lever each time to project the ball to consistent heights, either by dropping a book from a consistent height, or by using a constant force with their hand. Then, while using this consistent force they can measure the height the ball is projected for different positions of the fulcrum. Suggested worksheet attached for recording data.

Students can be taught standard notation if using a drawing to record their results: the lever is drawn as a straight line and the fulcrum is a triangle under the line in the correct position. Students should add arrows showing where they apply force (“force in” or “effort”), and where the resulting force is felt to project the ball (“force out” or “resistance”). They should add notes or parts to their drawing to indicate the height the ball is projected. Older students might want to use metre sticks to measure how high the ball goes, and record results.
Alternatively, numbers along the lever arm can be used to record the position of the fulcrum.

This activity can be used to conclude that:
1. A lever can change the direction of a force (your hand pushes down, the foil ball goes up). Note that other classes of levers do not change the direction.
2. The more force put into the lever, the more force out, so the ball goes higher.
3. When the fulcrum is nearer the applied force, the ball goes higher.
And another feature of the lever to point out:
4. The different ends of the lever move by different amounts, depending on where the fulcrum is placed. (When one end moves further it pushes the ball for longer and can project the ball higher.)

Students may also start experimenting with balancing the lever with different sized foil balls (like a see saw). See this balancing activity for further ideas to suggest if they go this route.

Students can also use these materials and be given additional materials to try lever free experimentation, for some less structured exploration of levers, probably best done after these more structured activities.

1. Try lifting a friend/concrete load using one fixed pulley:
Attach one pulley to the supporting bar with a short length of rope. Feed the long rope through this pulley and tie it off at the seat/concrete block.
Pull on the free end of the rope to try and raise the person/load up. This will most likely be hard, and not possible for some students.
The pulley allowed you to pull in one direction and move the friend the opposite direction - it simply changed the direction of the force.

2. Try pulling a person up using four pulleys:
Tie two pulleys to the supporting bar with two short lengths of rope. Add a loop of rope to the seat or load, and through the eye hooks of two pulleys, while knotting the rope between the pulleys to keep them spaced apart (see photos).
Feed the long rope through one of the upper pulleys, then through a lower pulley, then through the second upper pulley, then through the second lower pulley, then finally tie the rope off at the supporting bar. Pull the whole system down to reach the ground, then tie off the other end of the long rope to the seat or concrete blocks.
Pull on the free end of the rope to raise the person/load upwards. Make sure students are pulling hand over hand, so that the rope never runs out (act as a brake on the rope act where they are holding it). Do not allow them to pull the person or load too high.
The point is for them to feel the force difference between this pulley set up and with the one pulley. It will be much easier to pull up with the composite pulley system. This is because there are now four ropes pulling the person/load up (count them with the students) and they share the force. You only need to pull on the free rope with 1/4 of the force of the one-pulley system. BUT you need to pull four times the length of rope through the pulleys to raise the load by the same amount. The total amount of work is the same with each pulley system: a product of the force and the distance over which the force is exerted.

Look at photos of cranes which have multiple cables extending from the load, allowing the machinery to lift a greater load with the same force from a motor. (More cables will need to be pulled through though.)

Set up stations or give students a collection of levers to try.
They can use worksheets to record what class of lever, or the location of the fulcrum and the forces, in each lever.

Class 1 levers:
The fulcrum is in the middle of one (or two) rigid rods. The force in is at one end of the rod and the force out is at the other end.
Scissors cutting paper
Claw hammer removing nails from wood
Hole punch
Clothes peg
Tongs (that open and close like scissors)
Can opener (look closely to see where the rivet and cutter are placed)

Class 2 levers:
The fulcrum is at one end of the lever arm(s). The force in is at the other end of the lever arm(s). The force out is in the middle of the lever.
Nutcracker and nuts
Garlic press
(Wheelbarrow - purple arrows)
Pop (or beer) bottle opener (harder as fulcrum and force out are close together)
Car door

Class 3 levers:
The fulcrum is at one end. The force in is in the middle. The force out is at the other end, and the ends move further with less force.
Stapler
Tweezers
Tongs (with the hinge at one end)
Chopsticks
Stapler remover
Shovel
Broom
Fishing rod

With more space and/or outdoors, add tools from the garden/woodshop:
broom (class 3), wheelbarrow (class 2), shovel (class 1), rake (class 3), crowbar (class 1), wrench (class 1), hedge clippers (class 1)

A see saw is a class 1 lever. Hockey sticks, baseball bats and many other sport equipment are class 3.

One end of the lever moves over a greater distance but with less force, while the other end of the lever moves less far, but with a greater force. Class 1 and 2 levers, we generally move the "force in" (or Effort) end of the lever over a larger distance, but little force is required, while at the other end of the lever ("force out" or Load end), it does not move so far but with a lot of force - enough force to punch a hole or crack a nut.
Class 3 levers, we generally move the "force in"/Effort end of the lever less far but with a greater force, while the other end moves further but with little force, so allowing controlled, fine movements to pick up materials.

Introduce students to the parts of a lever, including standard notation for drawing a lever. The “lever arm” is simple a rigid rod, drawn as a straight line. The “fulcrum” is something that the lever can rest upon and tip back and forth over (also called the “pivot point”), drawn as a triangle under the lever. When a lever is in use, we push on one end and apply a force to the system, called the “Effort”. The lever moves and outputs a force at the other end of the lever arm, called the “Load”.
Tell students that they will be experimenting with levers, and that they will use this notation for any recording of results.

Feeling the force on a lever
Set-up as a group activity with a lever (or two or three) in the centre of an area that the students can sit around OR set up as four stations that student groups can rotate through.
Students (one at a time) try lifting the brick by pushing on the other end of the lever. Then change the position of the fulcrum in the central lever (e.g. nearer to the brick), or move student groups to a new lever with a new fulcrum position. Students should compare how much force is needed to lift the brick compared with the first fulcrum position. Move to a third, then maybe fourth, lever and compare the force needed to lift the bricks. If appropriate (i.e. if the students have enough information from previous tries to make an informed guess), ask students to predict how hard it will be to lift the brick before they try the last lever, compared to the other tries.

Set-up as stations: set up three or four levers on desks, with their fulcrum in a different position. Mark with tape the location of each fulcrum on the lever, so that if it gets moved through use, students know where it should go. Make sure that one station has the fulcrum very near the brick and one is far. Students try a lever, then move to a new station.

Students should find that when the fulcrum is near the load, it is easy to push down on the lever, but when the fulcrum is far from the load, it is very hard (if not impossible).

Students can draw what they discover using standard notation:
The lever arm (plank of wood) is drawn as a straight line, and the fulcrum is a triangle under the line in the correct position. Use arrows to show where force is applied (at one end of the see saw - also called the effort), and where the resulting force is felt (under the concrete weight - also called the load).

Ask the students how the height of the ends of the see saw varies as the fulcrum is moved. They can measure the distances for more accurate recording of the results.
Less force over a greater distance (with the fulcrum near to the weight) is an easier way to lift the weight. However, in this case the weight will not move as high.
The amount of work balances: less force over a greater distance (at one end of the lever) balances more force over a smaller distance (at the other end).

Measuring and graphing the force on a lever
Demonstrate to students how to set up their lever, while referring to the drawing on worksheet. Tape the 500g weight (the Load) to one end of the meter rule. Tape a spring scale hanging from the other end. Lay the lever on the fulcrum then slide the system to the edge of the desk so that the spring scale hangs down just over the edge of the desk (see photo).
Show students how they will pull down on the spring scale, read off the force (Effort) required to lift the other end of the lever, while also measuring the highest point that the Load end reaches.
Show students the table on the worksheet where they will record their data. Ask them, for each position of the fulcrum, to make a drawing using standard notation showing the approximate position of the fulcrum, and to record the effort (in grams) that the scale reads for each distance (in cm) that the Load is raised by.

Finally, stress that it is important that the spring scale only just hangs over the edge of the desk, enough to take a reading but no more, so that the distance moved is recorded accurately. (If the lever hangs a long way off the desk, the lever can be pulled down past the level of the desk, so raising the other end to a random height.)

Allow students to set up their levers and record their data, while assisting as necessary to get accurate results.

Once students have all recorded data for several fulcrum positions, ask them to graph their data on the graph paper of the worksheet. See photo of a student’s graph is shown in the photo to illustrate that the data will not form a perfect line (as it is real data!), but a line can be drawn through the points with a ruler.

For a class discussion of the results, transcribe one set of data onto the board.
Ask students how the Effort and the Distance are related [as one increases, the other increases]. Ask why zero effort is not at zero height [because of the height of the fulcrum].

(If your lever bends a little with the fulcrum near the Effort and the Load out on a long arm, use the situation to discuss fair testing. If the lever arm bends a little, the distance will not be measured accurately. Hence for the testing to be completely fair, a different lever arm that is both light and strong is needed.)

Now step through the concept of trading force for distance. With a lever to demonstrate, review together at how the fulcrum position affects the distances moved at each end of the lever. Show that when the effort moves over a large distance, the load moves a small distance, and vice versa. The force is also greater on one end and smaller on the other - but opposite to the magnitude of the distance. Force and distance are traded at each end of the lever. Reiterate this important concept: at one end of the lever the force is greater and the distance is smaller, while at the other end the force is smaller and the distance is greater. This is an important concept for understanding how levers work.

Now help students to understand how the trade of force over distance can be useful to us. With a little force at one end of a lever, you can move something heavy at the other end over a small distance. Or, if you have a lot of force at one end of a lever, you can move something lighter over a greater distance at the other end. Tools that we use frequently exploit this concept. (Follow with the household levers activity.)

Assemble the rainbow.
Sort the coloured rocks on to the colours of the rainbow.
Some rocks probably won't match - arrange these into your own rainbow.

Compare the rough and polished jade. The polished should be much more colourful.
Jade is mined in BC. I tis a semi-precious stone used to make jewelry.

Look for the many colours in bornite.
Bornite is a rock mined in BC. It has copper metal in it, which is extracted and used to make coins and many other things.
Look at pennies, loonies and toonies. The yellowish colour in them is copper.

Review or explain how smell works:
Something smells because small molecules leave its surface and float in the air. When these molecules enter the nose of an animal, they trigger the smell sensation. (Specifically, the small smell molecule fits into a larger receptor molecule at the end of a neuron in the nose membrane. This triggers an electrical signal along the neuron to the brain.)
Different smell molecules activate a different combination of smell receptors, and so send a different pattern of neuron impulses to the brain, which are interpreted as different smells.

Run the activity:
Best if students are sitting in a circle.
Explain to students that they will smell plants and compare their smells to map which smell molecules they have in common.
Write the names of the plants to be smelled in a circle on the board. I used cedar, rosemary, lavender, grass, a green apple (cut open) and a sweet-smelling flower (e.g. lilac).
Pass the plants around the circle, and ask the students to smell them all. They can rub the leaves between their fingers to release the smell molecules if necessary.
Students should compare the plant smells, and tell you which ones smell similar. They will want to discuss what they smell, and it is almost certain that different students have different opinions about which plants smell similar - this is fine, as smell is a complex sense and everyone smells things a little differently.
If students need a cue to try and focus on the smell, give them descriptor words for smells: do any of the plants smell sweet, or musty, or fresh...
For each student that finds two plants that smell similar, draw a line between their names on the board. So if many students match up two plants they will have many lines between them, and plants that fewer, or no students, find a similarity between will have few, or no, lines joining them.

Once the board has many lines on it, explain to students that the reason some plants smelled similar to them is because they release the same smell molecules. Find a pair of plants that students matched up, and attach the pictures of the smell molecules they have in common next to the relevant plant names (refer to the list below). Make sure that students can see the molecule pictures and that they are repeated next to plants that smell similar.
Only post the molecules of plants that students have matched. If students match plants that there are no common smell molecules listed for, discuss that they likely do give off the same smell molecules, but you don't have the images for them - smells are made up of many molecule types, and we are only looking at some of them here.
Discuss why students make different matches: each of us smells a little differently, so we will pick up on different smell molecules in the plants and make different matches.

Smell molecules and plants that they are in:
Eucalyptol molecules are in cedar, lavender and rosemary smell.
Pinene molecules are in cedar and rosemary smell (also pine and other coniferous trees).
Hexenal molecules are in grass and green apple smell (it is released when grass or green leaves are damaged).
Geraniol molecules are in lavender and sweet-smelling flowers (geranium, rose etc).
Linalool molecules are in rosemary, lavender, sweet-smelling flowers (also some herbs e.g. coriander).

Final discussion on smell and how it often triggers memories. We each have our own associations with them, depending on our experiences as we grow up. Students can share any smell memories.

Spray the spider web with white paint.
Bring the black paper behind the web, and slowly move it forwards to catch the web on the paper. Fold the supporting threads behind the paper.
Laminate the paper and attached spider web.

Spiders make many different web shapes:
The orb web has sticky threads, catching insects that fly into it (top left in the spider web image and attachment).
A net-casting spider dangles a tiny web from its legs. It drops the net onto passing insects top right in the spider web image and attachment).
Sheet webs have dense mats of fine threads. Insects get trapped in them (bottom left in image and attachment).
The angling spider makes a line of thread with a sticky drop on the end. It swings the silk line to catch insects, then pulls them in (bottom right in image and attachment).

Loop the elastic bands over the nails to build spider webs.
Make the same shapes as a real spider web, or design your own.

Some spiders are camouflaged to hide from predators.
Hide each spider in its habitat: lay the spider over each habitat and find where it is best camouflaged.

Roll up your sleeves to expose the tip of your elbow.
Push one pointer finger against the flap that closes your ear (the tragus).
With your other hand, pick up the tuning fork by the handle end.
Hit the branched end of the tuning fork hard on your knee or a surface that will not get damaged.
Press the ball of the tuning fork against your elbow bone.
Can you hear the note from the tuning fork? If you can't, try hitting the tuning fork harder and pressing your finger more firmly into your ear.

With someone to help you, you can also hear the sound if the ball of the tuning fork is pressed against your forehead, your chin, or other bone in your head. Block both ears, while your partner presses the vibrating tuning fork against one of your bones. How far away from your head can you place the vibrating tuning fork and still hear it?

For younger students, ask them to push closed the flaps in both their ears, and point their elbows towards you. The teacher handles the tuning fork.

The sound vibrations from the tuning fork travel through your bone and directly to your inner ear. We usually hear sounds through the air, which are received by our outer ear (our ear flaps) before being transferred to our inner ear.

Snakes do not have outer ears. Sound vibrations from the ground vibrate their jaw bones, which transmit the sound vibrations to their inner ear directly (as in this activity).
They are very sensitive to sounds made by small prey running nearby.

Whales hear low frequency sounds, that have travelled a long way through the ocean, through the bones of their skull.