This in a fun and interactive way for your students to learn what the job of a stem is. As a teacher you will need: celery, water, red food coloring, and the worksheet at the bottom of the lesson. In this lesson, students will compare regular refrigerated celery to limp celery, as well as celery that has been sitting in water to celery that has been sitting in red water. You can use this lesson as an experiment to start off a research unit, or you can use this as a stand alone lesson. By the end of the lesson, students will have a better understanding of what the job of a stem is.