You will need

Long Sleeved Cardigan
2-3 years (22in Chest) - 4 Balls
4-5 years (24in Chest) - 4 Balls
6-7 years (26in Chest) - 5 Balls
8-9 years (28in Chest) - 6 Balls
10-11 years (30in Chest) - 6 Balls
12-13 years (32in Chest) - 7 Balls

Short Sleeved Cardigan
2-3 years (22in Chest) - 3 Balls
4-5 years (24in Chest) - 3 Balls
6-7 years (26in Chest) - 4 Balls
8-9 years (28in Chest) - 4 Balls
10-11 years (30in Chest) - 4 Balls
12-13 years (32in Chest) - 5 Balls

4mm and 5mm Needles
Cable Needle
2 Buttons