Here's an easy craft to do with the children. First, buy white eggs and hard boil them.
Next, fill a container half full with water and add between 5 - 20 drops of food colouring, depending on how strong you need the colour. Add a splash of white vinegar and mix together. Place the egg in the container and make sure it is covered with the water. Soak in the dye until the egg is the colour you desire.
Leave on a paper towel to dry and then decorate them any way you wish.