ingridscience

Either use as a demonstration, with discussion as each part of a leg is found.
Or partially dissect a leg before hand (remove skin and expose some tendons) for students to discover the parts.

Step by step dissection of the leg and the function of the parts revealed:

1. Find the muscles
If there is skin, peel it off the chicken leg. The pink meat under the skin is muscle.
Find the lower leg (drum stick) and upper leg (thigh), and the knee between them. Also find the ankle at the end of the drumstick (the foot has been cut off).
The chicken can contract (shorten) one set of thigh muscles to bend it's leg at the knee, and muscles on the other side of the thigh to straighten it. The same happens in our leg - muscles on the front and back of our thigh respectively straighten and bend our leg.

2. Find the tendons and the muscles they are attached to
(The tendons attach the muscles to the bone, so that when the muscle contracts it pulls on the bone and makes the leg move.)
Cut the chicken leg down to the bone around the ankle. This should reveal the strong, white, stringy tendons.
You can feel your own ankle tendons: the large Achilles tendon at the back, and many smaller ones in front (easier to find if you raise your foot).
On the chicken leg, follow the tendons up to a muscle and carefully separate the muscle. This will require carefully slicing through a thin membrane. The several muscles of the lower leg can be separated out. Each muscle can work independently and with others so the chicken can move its lower leg in different ways.

3. Find the leg joints
Cut through the muscles over the knee to reveal the two bones joining at the knee. You might also find the connective tissue protecting the bones and preventing them from rubbing directly against each other, and the ligaments holding the bones together. Bend the chicken leg at the knee and watch how the bones move past each other - this is a hinge joint. Your knee bones work in a similar way.
Cut through the muscles at the hip joint at the top of the thigh, to find the hip joint where the upper leg meets the leg (a ball and socket joint).

4. Find the bones
Just like us, the lower leg of a chicken has a large bone (the tibia), and a small fibula. In humans the fibula runs the length of the lower leg, but in a chicken it is a tiny spiky bone, extending only part way down the leg.
Both chickens and humans have one bone, the femur, in the thigh.

Explain to students that they will be measuring how fast their neurons can transmit information in this activity. They will be using their neurons to see and to contract their muscles, as well as neurons that send messages between these two processes.

Give each pair of students a ruler. Demonstrate how one student rests their arm on the edge of a table their hand hanging over the edge, and holds their thumb and index finger a couple of cm apart. The other student of the pair holds a ruler so that the 0cm mark is between the thumb and finger. Without warning, the ruler is dropped and the partner closes their fingers on the ruler to stop it as quickly as they can.
Students should record the catch distance each time, doing several trials before switching roles with their partner.
They can try the activity with their dominant and non-dominant hand, as well as being distracted while talking about something different.

Ask students to find the mean of their data, and record their average catch distance.
Convert catch distances to reaction time:

From https://letstalkscience.ca/sites/default/files/2020-11/Testing%20Reacti…

Hockey goalies, and other people in high-speed sports need to have very fast reaction times. They would be able to catch the ruler at about 11cm, giving a reaction time of 0.15 seconds. Some students might have reaction times this fast, but most will fall between 15cm and 20cm (reaction times from 0.18 - 0.2 seconds).

With our rulers, our students got average catch distances of 10, 23, 19, 15, 10, 16, 18, 18cm.

Discuss how with any reaction time, it is amazing how fast the processing happens.
Show image of pathway, then trace pathway on a real brain if possible: the eye sees the ruler drop and a message is sent along a neuron to the thalamus in the centre of the brain, from which another neuron sends a message to the visual cortex. Once the image of the ruler dropping is perceived, there is a signal to close the fingers, down one neuron from the motor cortex to the spinal cord. Then a second neuron all the way from the spinal cord down the arm to the finger muscle. Then the finger muscle contracts.
All this takes milliseconds. The slowest part is the message passing between neurons; the neurons themselves transmit the electric message very fast.

Try two activities, to experience how your muscles help you keep balance.

1. Stand with your legs apart, your feet spaced at least as wide as your shoulders.
Try to lift and hold your right foot off the ground without moving your upper body - you'll need to put your foot down again quickly as you start to fall.
Now lift your right foot off the ground while allowing your upper body to move, so you can keep balance one one foot. Notice how you changed your body position so that your upper body is over your left foot. Your left leg muscles worked together to shift the weight of your body over your left leg. And now that you are standing on one foot, the muscles in your left leg are constantly adjusting to help keep your balance.
For younger students, it might be best to start with them standing against a wall to prevent them from moving their upper body: Put your left shoulder and foot against a wall. Try and lift up the right foot. It is impossible because you can't shift your weight to balance because the wall is in the way.

Dancers and gymnasts have strong leg muscles because they use them constantly to balance in many different positions. To be able to hold a pose, the dancer's/gymnast's centre of gravity must be directly above the area of contact with the floor.

2. Put your back and heels against a wall. Try and touch your toes without moving your feet.
Now try the same movement without the wall.
A wall makes it very hard to stay balanced while bending down. Without the wall, our muscles work to shift our body dramatically to keep our weight centered over our feet, so that we can stay balanced. We are often not aware of these constant adjustments our muscles are making to keep us balanced.

During sports our body moves a lot. As we kick, hit or move an object, many forces act on our bodies. Our muscles are constantly working to counteract these forces and keep us balanced.

Simple activity (works well as a demonstration with discussion):
Drop two paper plates side by side at the same time. They should hit the ground at about the same time. Repeat the drop several times, so that students are convinced they fall at the same rate.
Then crumple one of the plates, then drop them side by side again. The crumpled plate will hit the ground much faster.
The plates are the same weight, so the downwards force on them from gravity is the same.
The difference is the air pushing upwards on the plate - with the greater surface area of the flat plate, more air is pushing up on it. This greater upwards force negates a lot of the downwards force. The crumpled plate has a smaller surface area, so less air is pushing up on it, so it is not slowed down as fast, so hits the ground faster than the flat plate.
Students can suggest ideas, like uncrumpling the plate, or placing a crumpled plate on a flat plate and dropping together. Fuels good discussions. Some students can't help falling into the explanation that the crumpled plate is heavier than the other (that is why it is faster). Doing all these variations and combinations allows them to think extensively around the concepts.

More complex activity:
Drop pairs of objects from the same height, and record which hits the ground first (do three trials for each).

In a group discussion compare the objects of the same shape (e.g. chopstick, pipe cleaner and straw e.g. square of wood, cardboard and paper of the same size) - which will likely fall fastest to slowest in that order.
Ask why one falls faster than the other - students will think of weight. Weigh and record the items weights (we had chopstick 3g, pipcelaner 1g and straw 1/2g of one shape, then a wood tile 37g, cardboard square 3g and paper square 1/2g).

Compare objects of the same weight, but different shapes (e.g. chopstick and square of cardboard, or paper and straw). They all have the same force of gravity acting on them. Ask students why they fall at different rates - their shapes: the cardboard/paper is flatter, so hits more air molecules as they fall which push back up on the object to slow it down. This is called the force of air resistance (a kind of friction). The narrower chopstick or straw have less air resistance.

[This paragraph needs editing and cleaning up conceptually] Compare objects of the same shape, but different weights. The heavier objects will have a greater force of gravity pulling down on them, but surprisingly, this is not the full explanation, because on the Moon a heavy and light object fall at the same speed (see the Apollo 15 video of a hammer and feather being dropped: https://www.youtube.com/watch?v=KDp1tiUsZw8). There is no air on the Moon - it is the air on Earth, pushing upwards as air resistance, explains why the lighter object falls slower. The air resistance (pushing up) very quickly balances the pull of gravity (pulling down) on a lighter object, so it quickly stops speeding up. A heavy object has to speed up a lot more before air resistance balances out with the force of gravity, and in a relatively short drop height (as in our experiment) the heavier object is still getting faster before it hits the ground.

Summary: as an object falls, the force of gravity on the mass (called weight) and the force of air resistance pushing up (which depends on the shape and speed of the object) are both acting on a falling object. The speed that it falls is determined by how those forces balance out.
Objects keep speeding up as they fall, until they are moving so fast that the air resistance is large enough to balance the force of gravity. Then they have reached terminal velocity. This happens much faster with a lighter object.

Discussion:
In many sports, we design equipment and shape our bodies keep air resistance, also called "drag", to a minimum e.g. bike racers bend down to reduce air resistance and bike one behind the other to be sheltered from air resistance e.g. a bobsled is shaped to be as streamlined as possible, so reducing air resistance. e.g. skiiers and speed skaters wear suits that are very smooth, so reducing air resistance.
In some sports e.g. parachuting, we use air resistance to our benefit so that we do not land on the ground too fast.

Addditional surprising activity:
Drop the paper on top of the heavier wood tile (or a small book).
The paper will stay with the book and fall faster than on it's own.
The paper experiences no air resistance because it is on the book, so falls as fast as the book. The book falls faster than paper because it is heavier - the weight of the book overcomes air resistance.

Use one of two set-ups to feel the force of water resistance.

1. Fill a tray with water.
Cut out shapes from the stiff plastic e.g. different shapes of animal feet.
Drag the shapes through the tray of water to feel the water pushing against them.
Compare how much the shapes can push the water / the water pushes on the different shapes.

2. Fill a cylinder with water.
Mould similar-sized pieces of plasticene into different shapes e.g. flat disc, round ball.
Drop the shapes into the cylinder and see how long they take to fall to the bottom.

A more complex (but more exciting) set up of a similar phenomenon at water resistance: racing shapes through water.

Discussion:
Wider shapes can push more water.
The water pushing back on the shape is called water resistance, or drag. The more water that hits the object, the greater the drag. More drag will slow down an object more.

Applications:
Animals that live in water will have wide feet (duck, otter, beaver) or feet with flaps that can fold out (grebe). These wide feet can push more water and move the animal through the water faster.
Canoe paddles are wide so that they can push more water to more effectively move a boat forward.
To reduce the amount of drag, boats are built with a streamlined shape so that they slide through the water more easily.
Swimmers shape their bodies to be as streamlined as possible to reduce the drag as they move through the water.

Mix 1 tspn fibre powder to the half cup of water and stir until the grains are evenly mixed.
Optional: for better taste add 1/2 tspn drink mix. Stir in.
Optional: for colour add 1 drop food colouring (e.g. 1 drop blue dye in orange flavoured drink mix makes a great snotty green colour). Stir in.
Microwave until it bubbles (30 secs to 1 min)
Take it out, stir. briefly, and allow to cool for a few seconds. Microwave again until the bubbles rise up the container.
Repeat: Take it out, stir. briefly, and allow to cool for a few seconds. Microwave again until it boils again.
The more times you repeat this cycle, the more rubbery your flubber will become. 3 times minimum. Make sure it cools a little between heating.
Pour out onto a plate for and allow to cool completely to see the final consistency. (Even once it has cooled completely, it can be microwaved again to become more rubbery.)

If with these directions, it is still too goopy, try with less water (the orange slime in the pics is with 1/4 cup water, the green with 1/2 cup).

Though it might not taste great, it is edible as it is made from food-grade ingredients. But note that the fibre powder is a laxative, so nibble in moderation. (The recommended children's dose for a laxative effect is 4 Tablespoons (48g) over a day.)

Store in a ziplock bag.
Do not eat if it has been stored for a while and harmful microorganisms might have started growing in it.

The science and chemistry of flubber:
Psyllium (abbreviation of psyllium hydrophilic mucilloid; also the name of the plantain plant whose seed husks it comes from) is used as a food grade fibre. Fibre is the part of plants that our bodies cannot digest, and is found in many grains, beans and vegetables.
Psyllium (a kind of fibre called mucilage) is made up of long protein and sugar molecule complexes. (Other common fibres such as cellulose and xanthan gum are long chains of sugar molecules.)
Mucilages (which behave similarly to "gums") mix with water, to make a goopy mixture. The mixture is made up of liquid water droplets suspended in the solid mucilage. The term for this kind of mixture is called a "gel", which is a kind of colloid (see attachment for summary of different kinds of mixtures).
During the making of the flubber, the heat from the microwave increased the rate that the water was dispersed in the mucilage.

Introduce the sports equipment, ideally with a game, or show the equipment.
Demonstrate how it is a class 3 lever, with the length of the equipment being the lever arm, the hand gripping at the end is the fulcrum and the other hand (most sports) or the index finger of the fulcrum hand (tennis racquet) produces the force of the swing (the "force in" on the image, or the "effort").
The ball will be hit at the other end of the lever from the fulcrum (the "force out" on the image or the "load").

Do an activity that shows how the ball goes furthest when the ball is hit at the end of the lever arm, rather than nearer the fulcrum, and this is why the sports equipment has some length to it:
1. Hold a paint stick on the ground, and rotate it from one end (this is the fulcrum at one end of the lever and the force in just above it). Using the same force to swing the stick each time, either place a ball at the centre of the stick before hitting it, or at the end of the stick (away from the fulcrum) before hitting it. With several trials to ensure reproducibility, the ball hit with the end of the stick, rather than the centre, should go further. This is because the end of the stick moves faster (and further) as the stick rotates, than the centre of the stick. Therefore the end of the stick can transfer more energy to the ball and make it go further.
or 2. On a smooth floor surface with coins. Hold the paint stick (or ruler) at one end, use the other hand to hold the stick a little further up and rotate it so that it swings. Place coins at varying distances from the fulcrum, making sure they all start on the same vertical line, and swing the stick with the same force each time. (Optionally mark a point to which the stick is drawn back to, then swing with as much force as possible each time, to be consistent.) Note how far the coins slide with varying distances from the fulcrum - if this is done on a long piece of paper, the distances the coins move can be marked each time. The coins should generally go further when they are hit with the end of the stick, rather than the centre. Do several trials and look at the average to see this result.

The same principal applies when using a tennis racquet, hockey stick, baseball bat etc: the equipment length is the lever arm, the hand at one end is the fulcrum, and the other hand (or the index finger in the case of the tennis racquet) is the force in or effort. The force out at the end of the lever arm is the greatest, as the lever is moving fastest there, so the player tries to hit the incoming ball as near to the end of the equipment as possible, to make it go as far as possible.

Note that although the end of the lever arm is moving the fastest, it will actually have less force per unit distance than nearer the fulcrum. But as the ball is relatively light compared to the equipment this does not matter.

Tennis racquets, and hockey sticks to a lesser degree, have some elasticity, to store some elastic potential energy from the incoming ball, to give the energy back to the ball as it leaves.

Students can be instructed step by step on how to make the sound sandwich.
Or, they are given a model at each table group to replicate - they need to use skills of careful observation and small manipulations.

Make the sound sandwich as follows:
Loop the wide rubber band around one of the large popsicle sticks.
Push the coffee stir stick piece under the rubber band, near the end of the popsicle stick.
(Optional addition: Lay the small popsicle stick over the rubber band, near the other end of the popsicle stick.)
Lay the second large popsicle stick over the first, sandwiching the coffee stir stick (and small popsicle stick if used) between them.
Wrap the small rubber bands around the ends, to strap the large popsicle sticks together.
Blow through the large popsicle sticks to make the rubber band vibrate (making sure not to get it wet with your tongue).
(Optional if part of model: Move the small popsicle stick nearer or further from the centre of the sound sandwich, to change the tone of the sound.)

Once they have made it and figured out how to make a noise, ask how they think the noise is made (and how we hear it).
(Blowing makes the band vibrate, which makes air molecules vibrate. The vibration of air molecules spreads out and moves to our ears where it causes the vibration of our ear drum, which leads to the stimulation of neurons in our inner ear.)

Then add nuances of the noise maker:
The sound can be changed by blowing harder or softer (makes the band vibrate at different frequencies, therefore producing a different pitch).
Can you make a sound by sucking air through it?

Detailed instructions at:
https://www.exploratorium.edu/snacks/sound-sandwich