The best learning happens actively! When I wanted to teach my students about gardening, we collected and dried mustard green seeds until we had enough to plant. Then we went out to the small garden plot behind our classroom and planted the seeds.
After several exciting days of waiting, the tiny seedlings sprouted. My students helped water and weed the plants as part of every class, and learned lots of new gardening vocabulary. Finally, the great day came when the plants were ready to harvest. We carefully cut enough mustard greens to make ourselves a good salad!