Funny things: the elephant toothpaste!

One of the most important tools chemists have to explain chemistry is the experiment. Generally, teaching to young students is really hard, so funny experiments are important to attract them to our science. It is great to have the possibility to find a lot of funny experiments on Internet. By chance I found this beautiful experiment explains the decomposition of hydrogen peroxide, the role of catalysts in chemical reactions. Here there is a simple and safe recipe.
Materials:
• 125ml 6% Hydrogen Peroxide (also labelled 20Vol)
• 1 Sachet Dry Yeast (powder) + 4 tablespoons of warm water
• Detergent
• Food colours – optional (not cochineal)
• Empty bottle
• Funnel
• Plastic tray or tub
• Dishwashing gloves
• Safety goggles
* 6% Hydrogen peroxide (20Vol) is available in 400ml bottles from most retail chemists and cosmetics suppliers and some supermarket
Instructions:
1) Put the dry yeast in a cup, add 4 tablespoons of warm water and stir untill is well mixed
2) Put hydrogen peroxide (use the funnel), the detergent and some food colours into the empty bottle
3) Pour the yeast solution into the bottle, you will start seeing the production of foam quickly! The excess of the foam will pour out of the bottle!!!