Week 36 – Dichotomous Key Project

One month ago, we planted our vegetable garden.  It was the reward for several weeks of arduous labor (about which my kids are still complaining).  This week, we will observe together the miracle of biology: after a little more than 4 weeks, what began as a tiny little seed is now a plant with interesting and complex structures, well on its way to maturing into something that will produce food for us in a few months.  From the perspective of the plant, feeding us isn’t the goal.  The plant has domesticated humans by convincing us to cultivate it, thus ensuring the plant and its offspring survive for future generations.  Same with cats and dogs – we like to pretend we’re in charge, but really the creatures we love as “pets” have actually been stunningly successful at domesticating humans and getting us to feed, shelter, love, and protect them.  Who is really in charge?

But I digress!  Back to plants and our work for the week.  Your job is to look through the pictures of individual plants from the garden.  The pictures show the plants after 3 weeks of growth (they were taken last weekend).  The plants are labeled so you will know what you are looking at.  Take notes about the characteristics of the plants – you will need those notes to construct a dichotomous key.  (Click here for a refresher about dichotomous keys).  Your goal for the week is create a tool that can be used by a vegetable gardener to know which plants will produce which vegetable and to help the gardener know which plants are weeds and should be removed from the garden.


  1. Observe the pictures of garden vegetable plants after 3 weeks of growth (from seeds).  The same pictures in the link are also provided here as a slide show.  Use whichever is easiest for you.

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  2. Record (write down!) detailed observations in a Google Doc titled “Vegetable Garden Dichotomous Key – Your Name”.  This means, make a list of the 25 plants.  Write down detailed observations of each plant.  Your observations will serve as your evidence for how you construct your dichotomous key.
  3. In your Google Doc, organize the plants into groups based on similarities.
  4. In your Google Doc, create a dichotomous key to determine the identity of each plant through a series of questions.  Look for differences between the groupings of plants you created and then write the differences into questions.  For example, if you have a group of pink plants (which you do not!) while the rest are green, Question 1 might be: Is the plant pink?  If yes, go to question 2.  If no, go to Question 3.  Note: you can construct a flowchart instead if you find that easier. 
  5. Need help? Click here for a Dichotomous Key Project example.
  6. When finished, Share the Doc with Mr. Swart at david.swart@g.highlineschools.org

Return to Week 36 – Inferring with Evidence and continue working.

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