Step 1 - check they know what a fraction is. What does 3/4 mean? How could you draw a picture to represent it? If they are ok with drawing fractions and identifying them from pictures then I would move onto finding fractions of amounts. When they can do that then give them a sheet of paper with a 30cm line marked on it. Get them to generate a fraction by throwing 2 dice and putting the smaller number over the bigger one. They then find e.g. 2/3 of 30 and mark 2/3 on their number line. It's a nice way for them to "discover" equivalent fractions and practice of fractions of amounts at the same time.