I've another concept that may be of use for education purposes, and often done in school. Plastic bottles are non-recyclable and can be great for small vertical gardens inside or outside. There are many ways to make a bottle garden, either vertical or horizontal, depending on the kind of bottles you have on hand.
This vertical water bottle garden inspired me to make my first sets of water bottle gardens, just be careful not to have them in direct sunlight for too long, especially if they are clear, the gardens may be small and dry out quickly and grow algae or other things that will hurt plant roots.
Here is another video for other bottle garden inspiration.
Also, you could grow upside down tomatoes in a water bottle, this will need an already germinated tomato plant to be completed.
Finally, this video shows an idea of how to grow plants out of plastic bottles horizontally and out of plastic bags