I found a great site which offers a contest to the best innovative design. We entered the challenge two years ago and the scientists designed a game that could be played on Mars. They had to learn all about Mars: its gravity, red soil, atmosphere..etc.. and take those factors in to consideration when creating their idea.
The challenge we accepted this year is called Animal Smarts. The students were challenged to design a toy or game that would enhance the life of a zoo animal or pet which was suited to that animal's particular intelligence. Students chose an animal and watched videos of the animal in its habitat or "playing". This gave them ideas for a toy or game to design for that animal.
Kids Science Challenge is funded by the National Science Foundation. I like it because the website gives great background for each of the projects. They supply video and activities that can be used to help understand the challenge. The students don't actually have to make the design, just explain and diagram their ideas on paper.
We have some great ideas and we are sending them in next week.
One of our activities that we completed with the unit was to test our short term memory. We compared our short term memory to that of a chimp by trying to remember the order of digits from 1 - 9 after seeing them for a short time.