This workbook will help your child develop an understanding of subtracting the numbers one through five from whole numbers up to 20. By using this book, children will be able to understand the concept of subtraction by repeatedly tracing and reciting numbers both forwards and backwards and then gradually shifting to subtracting the numbers one through five. Kumon workbooks are based on the 'Kumon Method', an educational philosophy that aims at unlocking the full learning potential of each individual child.