The science-based Exploratorium in San Francisco has wonderful tools for educators. Two of their resources are the “after school activities” and the “kitchen science” experiments. Both have step-by-step instructions, “going further” sections, and explanations. Teachers can use the activities with students (appropriate for junior students) or use the video demonstration as a model for older students to follow when creating their own video taped experiments.

Ice Balloons

http://www.exploratorium.edu/afterschool/activities/index.php?activity=171&firstDisplayedItem=4