As your baby's hand coordination improves, he can really indulge his fascination with toys and other objects that catch his interest. When he gets hold of something new, he'll shake, bang, drop and throw it. And, of course, he'll put it in his mouth. He's also beginning to see how objects relate to each other. For example, he'll gradually understand that smaller things fit inside bigger ones but not the other way round. You can encourage his exploration with stacking cups and shape sorters.