My first year teaching chemistry, I was looking for a soap-making lab or activity that I could run in my chemistry class with 25-30 students working at the same time. I usually do this activity right before spring break, as it provides enough time for the soap to harden and cure (high school students are impatient to use their soaps right away, which you should not do with cold process soap). I have used the activity at different points in the curriculum: during intermolecular forces during acids and bases, and during stoichiometry. Although I know teachers who use soap making as a project during their stoichiometry unit, I chose to not emphasize the calculations as it would require more time than I have available. Simply making the soap easily fits in a 45-minute period.
Red dye #40 found in strawberry Kool-Aid and various cloth fibers can be used in a very simple experiment that can teach students about intermolecular forces. A video is included that describes the experiment and analysis of results.
It all started with a class my son and I took together at Marc Adams School of Woodworking (link is external). To make a long story short, we started on a Saturday morning with nothing and left Sunday afternoon with a custom built longboard. (Think skateboard but...well...longer).
Earth Day is just around the corner. If you are looking for some ideas to highlight environmental issues, the Journal of Chemical Education is offering free access to many articles and activities that you will find interesting.