Learning Resources Number Bonds Magnetic Demonstration Set. Help primary learners build number sense with this front of class demonstration set. Oversized resources allow teachers to easily illustrate fact family relationships and inverse operations on their magnetic white boards so the whole class can see. These classroom tools are ideal for building addition and subtraction skills, number relationships and an understanding of mathematical operations. Complete set includes three circles, three squares, four connecting lines and 45 magnetic counters. Counters measure 3cm. Includes multilingual activity guide. Suitable for ages 5+.