Children who have used Star Maths 1 will be familiar with the main characters and the planet Junketir. Sam and Amber are visiting their absent-minded Uncle Zak. He has asked them to help with making bars of metal in the Recycling Shed. This involves using 15 balls of scrap to make one bar, but the machine is unreliable and keeps losing varying numbers of balls. The children are charged with making the numbers up to 15 each time. When they have some problems, Uncle Zak shows them a chart and enlists Numberella, their maths guru, to demonstrate the number facts for 15. The children learn that once they know one fact they can rearrange the numbers to make another one.