Mello Jello in a Test Tube

I had been doing the mello jello lab in a petri dish as called for in the original published lab, but found it rather difficult in terms of materials management and set up. I re-worked it after "can't-remember-who's" lab using similar principles but set in test tubes instead of petri dishes. Much of the introductory material is lifted directly from the original lab. I've given full credit, so hopefully they won't come after me!

Mello Jello in a Test Tube

Diffusion Lab

I did this lab last year without lab sheets and had students record observations in their journals. I've put the lab sheets together. As usual, I may add to it next year - for example, I'd like to add a section on calculating the rate of diffusion, but I haven't had the time or energy to put it in yet. I may also play around with putting some starch into the mix and using starch indicator instead of food coloring. Still, the basic set-up will be the same.

I've seen other labs out there that use gelatin cubes placed in food coloring or other substances and incorporate surface area:volume ratios. For now I'm keeping it simple. I use a petri dish with gelatin and add food coloring to a well in the center, then measure the distance it diffuses over a 5 day period.

An added bonus, if you wait long enough, is the growth of mold on the surface, which is a whole other science lesson in itself on extra-cellular digestion and enzymes. I generally do this lab after the detergent enzymes with jello lab, so I try to get students to make the connection before I have to point it out to them. Anyway, here it is.

Diffusion Through Gelatin