Chemistry related activities 'Dissolve 1/2 ounce of alum into 1/2 pint of vinegar Dip a fine tipped brush into the solution and write your message on the shell of an egg. Let dry completely; then boil for 15 minutes. Writing cannot be seen on the shell, but is on the inside of the egg.' Having a whiteboard that is magnetic, (discovered that by chance) I use bright plastic-covered magnets (Staples - £1.99? - cheaper from some of the usual suppliers) to represent atoms in equations. The students love it and find it easier to remember as they can come up & move 'atoms' around.