Explore the power of the suns heat by blowing up a balloon on a bottle! Kids paint one soda bottle white and the other black. Once dry, they attach a small balloon to the necks of their bottles. Then, they put the bottles out in the sun for a solar reaction!
I've done this before with my Kinder class! It works! Make a balloon terrarium, add dirt, seeds, water, then blow up with pump. Tie a string to the end of the balloon and hang upside down in a window. I used radish seeds and they sprouted the next day! -- this site has good ideas for kinder/primary