I love seeing my creative students build models of things, but I hated trying to chase down missing projects at the end of a grading period. So, I changed it up! Now I have my students work in teams to make models in the classroom with a random pile of supplies such as plastic wrap, paper, craft sticks, beads, empty bottles, etc.
For the cell models, my biology students build a cell with a list of organelles, and then they have to justify why they choose the material they did for the model. For example, I have had cell membranes made of plastic wrap (Thin, flexible), cheesecloth (Thin, can let some things in but others have to stay out), wax strips (Made of lipids, flexible), and balloon parts (will stretch when more water is added). This activity really makes the students focus of the function of the cell parts, not just what it looks like in a textbook picture.
This word document includes a student direction sheet, teacher direction sheet, and a chart that could be used for self evaluation or as an assessment.
This activity takes about 2-90 minute blocks in my classroom. There are different ways you could evaluate the models by collecting them, having students fill in the evaluation sheet, videotape them talking about the model, etc. I have a high number of ELL students, so I like talking directly to them as often as possible instead of looking at just written work.
As groups finish I go around and interview students, asking them to tell me about their model. I check off things on the evaluation chart as they talk, and then ask a few questions. I don't ask about everything (Not enough time of course...), but if the student can answer about 4 questions from me I figure they got it. We also do a quiz the next day where students label the cell parts on a diagram and then match the function to the organelle.
Have fun with this activity, and please leave me feedback on how it went in your room!