Giant Magnetic Number Bonds: DEVELOP Number Relationships, Fact Families and Addition & Subtraction Skills Giant magnetic number bonds allow students and teachers to engage with Fact families and part-part-whole relationships as a Group Colorful, magnetic circles, squares, and counters are designed to demonstrate fact family and part-part-whole relationships for the entire class. This comprehensive set includes 3 circle and 3 square number bonds (8'' and 9 1/2 '' in diameter, respectively), 4 connecting lines, and 45 magnetic counters measuring 1 1/4 '' each.