Over the past few weeks we have been making a Kitchen Volcano. It is a really fun science project to do at home and also combines a little arts and craft; if you have an aversion to mess, maybe it's not your ideal project but the children will LOVE it. And there are good scientific principles behind it to discuss, so it is great for science-related show and tell, science fairs and home school projects.
The 'explosion' is caused by bicarbonate of soda and vinegar, and red food colouring, which are simple and cheap to obtain if you do not already have them in the store cupboard. You can have fun researching the reasons why it makes froth with your children (hint: it is basically a chemical reaction which produces gas). There are a couple of different methods to making an effective froth.
Another way of extending the task would be to research a couple of these different methods and experiment to find the best one, as I am sure that there are even more effective methods than the one we used.
A further step after making the volcano would be to bake sponge cakes - you could also then discuss why adding bicarbonate of soda to cakes helps in the baking process.
MAKING YOUR VOLCANO
I would recommend using a medium sized cardboard box (with one side and the top cut away) as a base - it minimises later mess and makes the volcano somewhat portable.
an empty plastic drinks bottle
PVA glue and water mixture (about half and half)
poster paints (red, and grey or brown)
First using sticky tape, secure the bottle to the base. Then scrunch up some newspaper into balls and loosely tape around the bottle to make a mountain shape. After this, taking strips of newspaper which you have dipped completely into the PVA glue mixture, lay them around the shape until you have something resembling a mountain. Be sure to leave the bottle mouth clear and open.
Leave the paper mache to dry for at least 8 hours. When it is hard and dry, using paints, make your mountain a little more realistically rock like. You can add a red lava flow at the top if you like.
MAKING THE EXPLOSION
red food colour
1/4 cup of vinegar
2 tablespoons of bicarbonate of soda
washing up detergent
The original method I saw for making a kitchen volcano simply states: Put the bicarb in the bottle. Add the red colour to the cup of vinegar. Pour into bottle. Stand back.
However, my husband read that if you put warm water and detergent in first you get a better fizz. This is the method that we tried and it was OK. The children found it exciting. I would have liked even more boom, but I am not easily pleased.
On a side note, I think you can't possibly put in too much colouring ;-)