Teachers are always look for another way to reinforce principles covered in class. To understand how a greenhouse works, students must understand the critical factors that go into play to make a greenhouse function. The problem is that this topic is super boring to learn.
So take a page from South Side Bee Branch FFA and have your students design their own greenhouse. As you can see they used:
But you can even add cardboard, tape, hot glue, and ton of other materials to help them make the greenhouse a desktop reality. Just remember, the key is that they must implement the necessary structures to that the greenhouse works correctly. Fans, vents, doors, tables, and outer shell don't need to function but they do need to be present so the students understand that you have to have them for a greenhouse to function correctly. We've got to sneak that knowledge in there somehow.
If you need some more inspiration, here's another topic on greenhouses. Not only are these good things to know before you let people "store" their plants in your greenhouse they can also provide a learning prompt where your students can explain why these reasons are valid.
We do have quite a few lesson plans and other teaching materials to help your Plant Science class keep going. Take a look here: Plant Science teaching materials