We found this recipe in a Martha Stewart podcast (we did not use the accurate US cup measurement but provided you keep the proportions rights it should work)
You need:
2 cups sugar
2/3 cups corn syrup
1/4 cup water
food colouring (we used red)
a few drops of lemon or orange oil (optional)
lollipop sticks
sprinkles or candies to decorate
Put the sugar, corn syrup and water in a pan over medium heat. Stir it until the sugar is dissolved and it boils. Then stop stirring but let the mixture on the heat for 7-8 minutes (if you use a jam thermometer it should reach 150 degrees. If you do not have a jam thermomether then drop a little bit of the caramel in a glass of water - if it hardens immediately then it is ready)
Now you need to work fast: put the mixture in a measuring jug. Add the colouring and oil and mix it all without stirring too much. Pour dollops of the mixture over a silicon sheet or a greased baking sheet (greased with sun flour oil in advance). Press the sticks and the sprinkles or decorations in. Wait until the lollipops get hard and cool down (just a few minutes)
The children found the caramel making process most interesting, as it looked to them as a physics experiment. The caramel is super-hot so please be extremely careful (it is a good idea to have ice cubes nearby in case you spill some caramel on your skin by accident). The main problem with this recipe is that it is impossible to stop the kids from eating the lollies...which are pure sugar of course...