I suggest you do an exercise that shows how to divide a group of items into smaller, equal groups. For example, give them 24 beans, then ask them to separate the beans into 2 groups, 3 groups, 4 groups, 6 groups, 8 groups, and finally 12 groups. Explain to them that this is the same as dividing the number 24 by each of these numbers. Visualization is really important when you're teaching division.