Whizzer Bags

Old tea-towel or scrap of fabric
40-50 cm lengths of ribbon
1m string
1 teaspoon of sand

Please read the safety warning before you start.
Cut a circle the size of a saucer out of the fabric and put it wrong side up on the table.
Lay the lengths of ribbon across the centre of the circle and weigh them down with sand.
Gather the circle up into a little bag and tie tightly with one end of the string.
You should now have a little bag with streamers coming out of it, on the end of a long piece of string. Now find a wide open space - these bags can travel!! Holding the end of the string, swing the bag round in circles - like a falconers lure - and when it has picked up speed, let go.....can you catch it again before it lands?

Polystyrene Print Blocks

Please read the safety warning before you start.
Take a chunk of polystyrene with at least one flat surface (old packaging material is fine) and draw a simple picture in soft pencil. Poke out the lines of the picture with a knitting needle or skewer. Paint the surface, and press down firmly on to paper.

Water Rockets


This experiment needs to be carried out under adult supervision.
Do not stand over the bottle when pumping it up as it might take off and hit you.

Empty 1.5 litre plastic bottle
Strong cardboard for fins
Parcel tape
Cork to fit bottle neck
Bicycle pump with flexible hose
Needle attachment for pump

Please read the safety warning before you start.
Cut 3 right-angle triangles out of cardboard, approx 15cm high and 8cm wide. Tape them to the top of the bottle - this will become the base of your rocket - leaving an overhang of around 3-4cm.
Make a hole right through the cork, just big enough to fit around the bike pump needle.
Fill the bottle half to two-thirds full with water and plug it firmly with the cork.
Put the needle attachment on to the flexible hose of the bike pump and insert into cork.
Stand the bottle upright on its fins and start pumping.
(NB. Older son recommends removing clothes before the final stage!)

Play Dough Recipe

1 mug plain white flour
mug salt
1 tablespoon veg oil
1 tablespoon cream of tartar
1 mug water with food colour added
A few drops of essential oil (optional)see note below.

Please read the safety warning before you start.
Mix dry ingredients together in a med/large pan.
Gradually add water, pour in oils.
Stir constantly over a low heat, until it forms a ball.
Knead when cool.

Keep wrapped in a covered container and will probably last several weeks.
This makes a lovely textured dough that can be used like any other play dough, it goes thought the machines a lot easier than many bought ones. If it gets trodden into the carpet, scrap off the excess, a cloth and tepid water should remove the rest easily.

If you are using essential oils to scent the dough please be careful with your choice of oil, many can cause skin irritation especially for very young children. Lavender is one of the safest. Careful of colours used too, a lot of children have bad reactions to them. Another educational slant is to make your own food colourings from things like onion skins or beetroot. History books or an internet search will find more.

Making Plaster of Paris Moulds

Please read the safety warning before you start.
Make up the above recipe, you can leave out the colour and essential oil if you want. You now have a dough you can use to cast plaster of paris models plaques, fridge magnets etc.

Put some dough into a container about twice the depth and about 2 cms larger than the item you want to make a cast of. It is best to use a separate container for each item otherwise they can get pushed out of shape.
Lightly brush the item with oil, to stop it sticking to the dough.
Press into the dough, remove, fill hole with plaster of paris, leave to set. When set remove from dough. There may still be a small amount of dough stuck to item, if so gently rinse in cold water. Leave to dry, paint and decorate to taste. We have just had a practice using some sea shells which turned out very with lots of detail. Dough can be reused many times.

Making Paper

NB This is a very messy activity and should be done outside in warm weather!!

Papermaking frame - *instructions for making one below
Large, deep tray - cat litter tray is ideal
Vilene - medium weight and sew-in type, not the iron-on
Old blanket or towel
Two pieces of flat board
Old paper - just about anything except glossy. Newspaper will do, but the paper you produce will be grey

Please read the safety warning before you start. Shred the paper into small pieces and place in the bucket. Cover with hot water and leave to stand - preferably overnight, but for at least a couple of hours.

Swirl the mixture around with your hand and then whizz a couple of mugfuls at a time in the liquidiser for about 30 seconds. Pour the pulp into the cat litter tray until it is around 1" - 2" deep. Add water to the pulp until the volume is roughly trebled - this bit is very much trial and error, and you will get better at judging it as time goes on.

Get your felts ready. Cut the vilene into pieces about 2" bigger all round than the frame. Fold the blanket/towel into a thin, smooth cushion and put one piece of vilene on top of it.

Now for the tricky bit. Don't be disheartened if it takes a few goes before you have the knack. Standing in front of the tray, swirl the mixture with your hand, then hold the frame in front of you, net-side facing. Using one smooth movement, lower the frame edge first into the tray, turn it through 90 degrees, then lift straight up. Jiggle it gently from side to side to spread the pulp evenly. You should now be looking at a very wet piece of paper.

If it looks too thin and patchy, scrape it back into the tray and add more liquidised pulp. If it is very thick and lumpy, add more water. Hold the frame until it stops dripping - once the pulp has settled, tilt it towards one corner to speed things up.

Tricky bit number two - again, it may take a bit of practice. Standing in front of the prepared piece of vilene on its blanket, roll the frame across it in one smooth movement: down on to its long side, splat on to the vilene, straight up on to its other side. With a bit of luck, you will have left your piece of paper behind on the vilene! If it hasn't gone to plan, scrape it back into the tray and try again.

Put a second piece of vilene on top of the paper and repeat the process until you have built up a stack of 5 pieces. Cover the last piece with more vilene. Transfer the stack to a piece of board, place the second board on top and press down very firmly. You can even stand on it, but don't jump up and down or it may break the paper! When all the water has come out, remove the stack from the boards and separate each piece, complete with its vilene backing. Spread it out to dry in the sun. Once it is dry, carefully peel it from the vilene, which can then be washed and re-used.

*To make your frame, you need:
Sturdy picture frame
Piece of plain, nylon curtain net
Staple gun.

Please read the safety warning before you start. Cut a piece of net about 2" bigger all round than the frame.
Staple the net to the sides of the frame, keeping it as taut as possible.
You are now ready to make some paper

'Robert Krampf's Experiment of the Week'

Here are two recent examples of the excellent science resource available free by email.

Each week he will e-mail you a new experiment that you can try yourself. He looks for experiments that are unusual, safe, dramatic, cheap, and fun. Since this list includes teachers, parents, science buffs, and students, he will try to give you a wide variety of things to try.

If you would like to receive the Experiment of the week, just send an e-mail to krampf@aol.com, asking to be added to the Experiment of the Week List. If you are requesting the experiments for your child's account, be sure it can receive e-mail.

Check out our web site at: http://www.krampf.com
Robert Krampf, PO Box 60982 Jacksonville, FL 32236-0982

Experiment - #174 Bad Chocolate?

It has to do with the white discoloration that you sometimes find on old chocolate.

You will need:

a plastic food storage bag
chocolate - I used chocolate chips and bar chocolate, using milk chocolate and semi-sweet chocolate.

Please read the safety warning before you start.
First, eat some of the chocolate. Notice the taste and the texture. Since we are going to change the chocolate, we need a control to compare the results with. Keep plenty of chocolate handy, as I found it necessary to refresh my memory frequently. I ate almost an entire bag of semi-sweet chocolate chips just to be sure I was familiar with their flavour.

Next, we are going to cause the chocolate to "bloom". That is the term that is used in the chocolate industry to describe the changes that happen in old chocolate. To do this, put some chocolate into the plastic bag. We want to heat the chocolate enough to partially melt it, without turning it into a puddle. I placed the bag on the dashboard of my truck and left it there for about 5 minutes. This worked much better than using the microwave, which tended to melt them too quickly. The chocolate should be soft, but should still be in a lump, not a runny liquid. If the chocolate melts completely, then get some fresh chocolate and try again.

Once you have some partially melted chocolate, place the bag someplace where no one will eat it. By the following day, you should notice quite a change. The surface of the chocolate probably is lighter colour and has very light coloured blotches. Break off a piece and taste it. Don't worry, the light splotches are not mold. While the taste has not changed much, you will notice a big difference in the texture. Instead of being smooth, the chocolate now feels grainy. Be sure to eat some more fresh chocolate to compare the two.

What has happened? The light coloured patches are cocoa butter, one of the main ingredients in chocolate. When cool enough to be solid, cocoa butter forms crystals. It is polymorphic, which means that at different temperatures, it forms different kinds of crystals. For chocolate to be smooth and creamy, the crystals must be very small. When we melted the chocolate and let it cool again, it formed larger crystals, giving it a grainy texture.

Cocoa butter is monotropic, which means that even if it does not melt, over time the small crystals will slowly change to the larger form. To prevent this, chocolate should be kept in a cool, dry place, but not in the freezer. If frozen, condensation can leach out the sugar, again causing white blotches. I feel that by far the best strategy for chocolate is to eat it all quickly, before it has a chance to go bad.

If you would like to be mailed more fun, practical, science experiments

Experiment - #175 Fireworks Colours


This experiment needs to be carried out under adult supervision as it involves fire and heating materials which can burn or explode.
Have you ever wondered how they get the different colours into the fireworks? If you want yellow fire, do you add yellow paint to the mixture? No, that would not work. To see how the colours get into fireworks, you will need:

metal paperclips
boric acid (from the pharmacy)
creme of tartar (from the grocery)
a clear, blue flame. If you have a gas stove, the burner will work very well. If not, you can use a candle, but the colours will be more difficult to see.

Please read the safety warning before you start.
Straighten several of the paperclips into long, straight wires. Dip the end of one of the wires into the water and then into the salt. Some of the salt should stick to the wire. Hold the other end of the wire with the pliers, so you don't burn your fingers and place the salted end of the wire into the flame. The flame should change to a bright yellow. Dip the hot wire into the water, so you don't accidentally burn yourself. Select a new wire and repeat the experiment with the boric acid powder. The flame should turn green. Try the creme of tartar and the flame will be lavender.

What is happening? Most of the light that comes from a flame is caused by solid particles burning inside the flame. As we have seen in past experiments, the yellow colour of a candle flame is caused by the burning of tiny bits of the element carbon. The blue flame that we started with does not contain solid particles, so it gives off very little light. By adding chemicals to the flame, we can give it different colours. The yellow colour caused by the salt is due to a chemical called sodium.

The boric acid contains boron, which produces green and the creme of tartar contains potassium, which burns with a lavender light.

This idea also applies to fireworks. When you see yellow fireworks, they contain the element sodium. Calcium salts are added to produce orange. Salts of strontium or lithium are used for red, and you get green by adding barium, boron or copper. Bright whites are produced by burning aluminum or magnesium metal. The next time you are "ooohing" and "aaaaahhing" over a fireworks display, keep in the back of your mind that you are also seeing a marvellous chemistry show at the same time.

If you would like to be sent a science experiment like this every week see above.

Safety Warning - Please Read

All of the experiments described on this site should be carried out with care and under adult supervision. Careful thought needs to be given to all aspects of safety, both to those conducting the experiments and to those watching or who might be nearby. Do not allow very young children to approach when you are busy experimenting and do not leave an experiment unattended at any time in case someone comes along who does not know what you are doing and gets hurt.

Before you start, get an adult to read through the instructions and discuss with you the precautions you need to take to do the experiment safely. If you need ingredients to carry out the experiment, ask before you grab them.

We have tried out the experiments we describe and they worked safely for us; however, we cannot guarantee that they will work for you and Free Range Education cannot take any responsibility for any consequences to you, or any other persons, of what you do, as we cannot be there to supervise you. Make sure someone does supervise you.

If you have any activities, experiments or craft ideas you would like to add to Fred Practical