ingridscience

This activity is how to dissect the brain before a lesson.
Follow the description of the parts of the brain, and associated activities, in the brain lesson.

The brain will probably already be cut, with left and right sides separated.
If not, slice it in half.
Look at the parts: cortex, cerebellum, mid and hind brain, corpus callosum: see labelled image at www.biologycorner.com/anatomy/sheepbrain/brain_dissect07.jpg

Discuss the functions of the parts:
cortex: thinking, reasoning, also optic, motor and olfactory areas.
cerebellum: fine motor control
mid and hind brain: basic processes such as breathing, heart rate, sleeping, waking etc
(See the Nervous System lesson plan for more details)

The intact brain can be stored in the fridge for days if covered in saran wrap to prevent drying out.

To see more cut the brain with a sharp penknife.
Cut parallel to the cut already made separating the left and right halves, but more lateral, to reveal the striatum and possibly the hippocampus.
Cut through part of the cortex to show the white and grey matter (the myelinated axons and the pinkish cell bodies).

Great images of a sheep brain dissection at:
https://www.biologycorner.com/anatomy/sheepbrain/
More nice photos at:
www.exploratorium.edu/memory/braindissection

Rocks may be made up of one mineral, or a group of minerals whose crystals have grown together. To help identify a rock by the minerals in it, there are a variety of tests including test for hardness and streak colour.
1. Testing for hardness:
The Moh’s scale is a scale of relative minerals hardness from 1 (talc; very soft) to 10 (diamond; very hard). It is used to help categorise and identify minerals. The hardness of a mineral can be measured by how easily it is scratched, either by other minerals of known hardness or with calibrated tools.
Students use a steel butter knife blade (scratched by minerals more than 5 or 6) to test the hardness of minerals to help identify them (see attached example). Other common materials to test for hardness are: fingernail (2.5), copper penny (3-3.5), steel nail (5) , pocket knife (5.5), window glass (6), steel file (6.5).
2. Testing for streak colour:
The overall colour of a mineral may vary if it contains impurities or has an irregular crystal structure, whereas the powder of a mineral has a more consistent colour. Scraping a mineral across a “streak plate” (unglazed porcelain) produces a line of powdered mineral whose colour can help identify the mineral. (If the mineral is harder than the streak plate (~7 on Mohs’ scale) another crushing method must be used.)
Scrape the minerals across the porcelain to examine their streak colours and identify them (see attached example).

These tests can be used to investigate locally mined minerals and their products e.g. bornite is mined in BC for its copper content (native copper sources are rarer). Much copper is recycled.

Go on a beach walk to find granite, or bring it into the classroom. Students will have seen it frequently, but likely not have taken notice.
On Vancouver beaches, granite (an igneous rock made up of different minerals) is often in the form granodiorite (black granite), which is speckled black, white, and grey/pink. Other common Vancouver beach rocks: smooth black rocks are likely to be basalt (igneous rock, cooled lava), and flat rough light brown rocks are likely to be sandstone (sedimentary rock made up of different minerals). Smaller pieces of quartz (a mineral) may also be found - clear or yellowish and more shiny.

Younger students can sort granite from other rocks by its speckled appearance.
Students can draw the outline of their black granite, then choose one part of it to draw in detail. (A pencil is sufficient to show the blacks, greys and whites).

There are three minerals in black granite: mica, quartz and feldspar. They make up the patches of colour in the granite.
Ask students to name the colours they find, using their flashlights (and optionally magnifiers with older students, but note that rock will scratch any kind of magnifier). Then write up the colours, assembling them into the minerals they are likely to be:
black, gold, silver (mica)
white, grey-blue, purplish (quartz)
yellow, orange, pink, brown (feldspar)
Name the minerals for the students.

As they look further at their rocks, and try and find the largest crystals they can (the largest "grain size'), circulate with samples of black mica, quartz and feldspar. Students can shine their flashlights on the samples you bring to see their colour and shiny surfaces better.
Alternatively, display the minerals for the students to look at independently at a station (see photo).

More information on the minerals in granite:
Another form of mica is white.
Quartz can come in other colours and makes beautiful crystals - show amethyst if available.

(Optional: show other rocks where the minerals are distinguishable).

Discuss how the black granite was made.
The black granite we are holding was once deep inside the earth. It is so hot in there that the rocks have melted (called magma) and all the minerals are liquid (show picture of a cross section of the earth). Imagine how hot it needs to be to melt rocks! As magma slowly moves towards the surface again it cools down, and this granite was made when mica, feldspar and quartz organized into their individual crystals as they cooled.
Some magma comes to the surface fast, and erupts from volcanoes. Magma from volcanoes cools very fast to form igneous rock, but it has much smaller crystal grain sizes than igneous rock that cooled inside the earth. Show volcano rocks - basalt (common here), pumice and obsidian. Can see gas bubbles in them.

Students model what happens to sugar molecules as yeast eats them.

Give each student/student group a sugar molecule (C6H12O6).
Tell them that one of the products as yeast breaks glucose apart is ethanol, and show them how to build it (CH3CH2OH). They should make two ethanol molecules.
Ask them to make two identical molecules with the atoms that remain. (Two CO2 molecules). It might be a challenge to figure out that there are two double bonds in CO2.

Once they have all made the CO2 molecules, spell out the name while pointing at the atoms "C-O-2", and some students may recognize the name and know it is carbon dioxide.
Ask what state of matter CO2 is (gas), and ask what might happen if this gas is stuck in bread dough (it will make it rise).

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.