If you don’t know what yet to do on a rainy day in Shanghai you might visit Children’s museum. It’s not much to do there, only 4-5 rooms available, even not on a busy day play-area was fully booked and it cost some money. They have also some activities but it’s to prebook and cost as well. You need to know chinese to book it so we could not. We spent there 30 min in total. I believe it’s could really nice there if you can get all information in English as well.