Investigate addition and subtraction bonds with this Year 2 Fact Families - Addition and Subtraction Bonds within 20 Discussion Problem! Unlike many problem-solving activities, this resource requires children to work together in pairs or small groups to find not one but numerous different answers. Pupils will use their prior knowledge of number bonds to find as many different number sentences as possible, using the numbers on the raindrops. Think your children are up to it? Then give it a go!