The human activities in which trees also participate are making tree houses, swinging on swings, hiding behind trees while playing ‘Hide and Seek’, having tea parties under them, making cool shades in summers, etc.

Trees make no shade in winter means that people do not lie under it in winters as it is already very cold and therefore, people look for warm places. The poet has mentioned how trees are useful in summers as they provide cool shade to people. He has contrasted this statement with the next one where he has mentioned that trees do not provide any shade in winters.