ingridscience

Just before the class, make a solution of 1:1 epsom salts:boiling water in a heat proof jar (using half a cup of each per table group). It will take a little while to dissolve all the crystals - heat in a microwave and shake alternately to make a clear solution.

Show the students how you make an epsom salt solution. Add a teaspoon of epsom salt crysals ito a jar of just-boiled water, and swirl until they dissolve. The salts seem to disappear, but the molecules of the epsom salts are in fact mixing completely in with the water molecules, to form a solution. Salt or sugar in water does the same thing.
Tell students they will be making a painting with a solution of epsom salts, but their solution is more concentrated (more epsom salts).

Distribute 1:1 epsom salt solution to shallow tubs on each table and give each student a piece of smooth black paper, a paintbrush and a flashlight.
Ask students to paint the epsom salt solution onto the paper, in any design they like. Emphasize to students that to get the best effect, do not repaint over a wet area, and make some deep puddles of solution. After a while, hand out flashlights for students to see better any changes on their paper.
Allow students to discover the formation of sparkly crystals, before discussion on what is happening.
As the water evaporates from the solution, the epsom salts will be left behind, and will organize themselves into crystals. Small crystals will form rapidly where the epsom salt solution is thin and water evaporates from it fast. In the deeper puddles, the water takes longer to evaporate and longer, spiky crystals have more time to form. Emphasize to students that to make the largest crystals, do not repaint over a wet area, as this will disrupt crystal formation that has already started.
Show students how the flashlights can be used to watch the crystallization process: shine a flashlight sideways onto the paper to see the sparkly crystals, and even see some of them growing as the water evaporates at the edge of a puddle.

Epsom salt crystals can also be seen growing on a knife, after dipping it in the epsom salt solution.

Students can fill out a worksheet to summarize and reinforce what the molecules are doing during dissolving and crystallization (see attachment).

Students can act out what the molecules are doing as the crystals form: some of them are water molecules and leave the group, while the others line up to form the remaining epsom salt crystals. Best in groups of 6.

If discussing crystal shapes:
The epsom salt crystal shape is technically a monoclinic prism - long with a lopsided, pointy tip. Whatever size the crystals are they will be this shape, but it is only really visible in the larger crystals grown in class or found in purchased epsom salts.

To make coloured crystals:
Mix watercolour paints with the epsom salt solution then layer thickly onto heavy white paper (e.g. watercolour paper). Overlapping colours will make nice effects.
It will take some time to dry, but is worth the wait.

Jar of epsom salts:
Epsom salts can also be grown in a cup or jar - simply dissolve the epsom salts in the water, and leave in an undisturbed place. A 3-D mass of crystals will form quite quickly. If there are no crystals once the liquid has cooled, tap the jar on a surface to initialize crystallization, and crystals will form very quickly - good to observe. Occasionally, crystal growth will be so slow that one or two giant crystals form.

NOTE: borax is toxic in high amounts. Do not eat (or allow pets to eat) this ornament! Best to keep in the classroom and hang up as a decoration. The borax solution that the students are handling is fine, though washing hands after the activity would be prudent.

Each student makes a shape out of the long pipe cleaner, small enough to fit in their cup without touching the bottom or sides.
Ask them to include a little hook so that their shape can hang from a half-pipe cleaner laid across the top of their cup.

When the shapes are ready, make the borax solution:
Either make it in each cup: put 3 tablespoons of borax powder in a cup, then fill the cup with recently boiled water and stir to dissolve the powder.
Alternatively, make one large batch of borax solution, and divide among cups. (3/4 cup borax in 4 cups water)
Likely not all the borax will dissolve. That is OK.

As soon as the borax solution is in a student's cup, they can lay the half-pipe cleaner across the top of the cup, then hang the pipe cleaner shape from it, so that their pipe cleaner shape dips into the borax/water solution (but does not touch the sides of the cup).

Leave the cups on a shelf where it will not be disturbed.
As the borax/water cools, box-shaped crystals of borax form on the pipe cleaner. It usually only takes an hour or so for many crystals to start forming. Leave overnight or over a weekend for best crystal growth in all cups. Often, borax crystals start to form on the side of the cup rather than the pipe cleaner - that's OK.

Once enough crystals have formed on the pipe cleaners, wash out the cup, and hang the pipe cleaner shape in the empty cup again, so that the borax crystals can dry.

The borax crystals sparkle in a bright light e.g. near holiday lights or in direct sunlight. On close inspection you can see the flat faces on the bigger crystals of borax.

Put all ingredients in a cookpot and stir until smooth.
Cook over a medium heat and stir until boiling.
Keep stiring and heating gently until it is the consistency of mashed potatoes.
Turn out onto a plate and cover with a damp, well-wrung kitchen towel to let cool.
Once cool knead until pliable.

The clay can be coloured with food colouring, or left white and
painted once it hardens.

When you have made your model, leave it to air dry - turning over every 12 hours or so.
It might take a few days to fully dry.

This recipe makes just over 2lb.

Mix ingredients together in a pot over medium heat.
Stir constantly as the mixture heats up.
Once it starts to make a paste, remove from the heat, keep stirring until it is all playdough consistency.
Put in a large ziplock back and knead every few minutes as it cools.
Keep sealed.

If some of the playdough dries out, just knead it into the mass again.

Double this recipe makes enough playdough for a class of 24 students, with a golf ball-sized piece of playdough each.

If using floral wire, fold one end into a triangle, push through a base or tape to a desk, then wrap it in a large piece of aluminum foil. Bend into a curvy shape. If using copper wire/steel strapping (first photo only) bend them into a curvy shape then attach one end to a desk or base.

Using tape or binder clips, attach the bulb/buzzer then the battery/batteries, from the base of the curvy piece made above.
Then from the battery, add on a longer piece of wire (home-made or purchased), which can easily reach to the top end of the curvy piece.
To the end of this long wire, clip a loop of tin foil or metal.

Test the circuit - when the small metal loop touches the curvy piece the bulb should light or the buzzer should sound. If it does not, redo the connections one by one and check each time for the bulb lighting.

To play the game:
Move the loop from the top of the curvy piece all the way down to its base without touching it. If you do touch it, you will close the circuit and the bulb will light/the buzzer will sound. How far can you go? If it is too easy, make the loop smaller, or the curvy piece more wiggly.

Students make a circuit containing a bulb and a battery, but keeping it open so that they can turn the light on and off.
Give students a morse code sheet (found online), and ask them to pair up to send each other messages with morse code. Try one letter at a time to start before sending a very short message.
Discuss the skill required to send and decode morse code fast.

Students build a circuit by taping the components to the board, initially with a battery and bulb, to test the circuit. The bulb should light when the circuit is closed (makes a loop).
Show them how to open the circuit up, so that they can place objects to test in the gap, to see if they conduct electricity (and therefore light the bulb). They may need to add an additional wire to make components reach.

Provide test materials, and also encourage students to walk around the classroom with their board, testing materials that they come across. (They may need to add in an additional wire so that their circuit can reach off the board for testing.)

Summarize together - metals conduct (that is why electrical wires are made of metal).
Plastic and styrofoam are insulators (that is why electrical wires are covered in plastic, and why we used a styrofoam base for our circuit).
Carbon also conducts.

For older students, materials conduct when they have free electrons that can move within the material to make a current.

Does water conduct? Try it. No. Why are we so concerned about electrical appliances in the bath? They are with much higher voltage, and it is only a problem if it goes across your heart.
Try other liquids, solutions of kitchen chemicals (baking soda, sugar, lemon juice, vinegar) - also see the electrolysis activity.

See electric circuits with home-made wires and bulbs for a very similar (and better) activity.

In your house, when you flick the switch, the light comes on. We’ll make our own light come on.

Here’s your bulb. Draw the bulb on the board. White paper behind a bulb to see the wire element better. When electricity squeezes through the thin wire it makes it so hot it glows.
Screw into a bulb holder and show how it connects to the bulb connectors.

Wire one end of the battery holder to the bulb. Wire the yellow piece of wire to the other side of the bulb holder.
Add a battery. Touch the wire ends together to light the bulb. Add blobs of foil to the end of each wire to make a better connection.
Draw the circuit on the board.
Students can join their circuits in a circle to light all their bulbs at once.

Add a cardboard base for each student to make the parts stay in one place: secure the battery holder with a loop of duct tape, and tape the bulb holder to the board.