“Substituted Sammy” – what makes something alive?


Lesson Plan: Substituted Sammy Google Slides (Public) modified from: “Substituted Sammy”: An Exercise in Defining Life, Donald F. Shebesta, The American Biology Teacher, Vol. 34 No. 5, May, 1972; (pp. 286-287) DOI: 10.2307/4443933

I love using this activity as an introduction to get my 7th grade students thinking about the idea of living vs. nonliving. How do we define life? How do we know something isn’t alive anymore? How are living things different than nonliving things? How are nonliving things different than things that were once living? What characteristics do living things have in common?

To start the lesson, we brainstorm and try to pin point what it means to be alive. Accept all answers and write them on the board.  After our brainstorming and discussion session, I draw Sammy on the board in one colored dry erase marker ( ie blue) and ask students to do the same. I explain that we are going to learn about Sammy and every time something about Sammy changes, I will draw it in a different color (ie red) and ask students to do the same in pencil.

As the story progresses, I also draw a dialysis machine, IV bag and stand, ventilator, etc… and essentially, end up drawing a robot at the end. This leads to some great discussions about what we can do now, and what we can’t do yet, in the medical field. It also brings up the discussion about the quality of Sammy’s life, at some point is he really living his life or just alive? I ask the students to give Sammy a percentage of “living” as we go through the slides, is he 50% living, 80% living, 25% living, etc and they give a wide range of answers. I then reveal it is a trick question, the answer has to be either 0% or 100%, you can’t be partially living, biologically speaking – you are either alive or not alive, there really is no quantitative scale. Quality of life is not a biological definition, instead it is an ethical issue and everyone has their own definition or belief system. (And then there is the gray area that Viruses fall into ;))