Gravity versus water up thrust

Class 4 have been finding out about different forces in Science, so far including gravity, air resistance, water up thrust and balanced and unbalanced forces. In this session, we tried out different experiments: 

 - What happens to the weight of an object when it is put in water?

-  Does it make a difference if a ball drops through air or water?

-  Which design of boat will be able to carry the most paperclips when it is put in water, before it sinks, and why?

Here are some photos...