Lesson Description

This lesson introduces learners to dichotomous keys for identifying mushrooms and challenges learners to identify mushrooms that they have found in the wild, at least to the level of family, if not genus or species.

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Associated Standards

**Under Construction**

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Essential Questions
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• What is a dichotomous key?
• What are the primary taxonomic ranks?
  
• What phylum houses common mushrooms?
  
• What phylum houses the "cup fungi"?
  

Enduring Understandings

• A dichotomous key is a tool used to identify things which poses a series of two questions which eventually lead to a narrow set of identifying characteristics.
• The primary taxonomic ranks include domain, kingdom, phylum, class, order, family, genus, species
  
• The Basidiomycota is the phylum containing all "club fungi" including all common mushrooms.
  
• The Ascomycota is the phylum containing "cup fungi" and other simple fungi.
  

Learning Objectives
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• Learners will use a dichotomous key to identify mushrooms to the family level.
• Learners will recognize whether a fungus is a basidiomycete or ascomycete based on familiar structures visible to the naked eye.
  

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Materials

• Paper
• Writing utensils
• Newspaper
• Wild mushrooms
• Multiple copies of ​David Arora's Mushrooms Demystified
• Magnifying glass, loupe, or microscope
• Spore printing supplies including black and white construction paper, bowl or cup to cover mushrooms

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Lesson Instructions

1. Background:
   1. Biologists use special field guides called dichotomous keys to identify wildlife. These field guides are called dichotomous because they feature series of two questions (is it this or that?)​​ which eventually lead to a narrow selection of choices that the biologist can use to determine what species of wildlife they are looking at. Dichotomous keys can help biologists identify organisms to varying levels of taxonomic rank, including domain, kingdom, phylum, class, order, family, genus, and species (and sometimes even further down to subspecies, variation, and form!). The fungi kingdom belongs to the Eukarya domain, along with animals and plants. Within the fungi kingdom, there are primarily 5 phyla, the Basidiomycota, Ascomycota, Chytridiomycota, Zygomycota, and Glomeromycota. As research advances, there may be more phyla identified, but for now, these are the primary ones that are formally recognized. For the purposes of this lesson, we will focus on just the Basidiomycota (club fungi) and Ascomycota (cup or sac fungi), which make up the bulk of fungi visible to the naked eye.
2. Anticipatory Set:
   1. Display an image of a basidiomycete and an ascomycete and ask learners to quietly write down the ways in which these two fungi are alike and different.
   2. Perform an identification exercise:
      1. Give each of the mushrooms an arbitrary name.
      2. Ask the learners what questions they could ask in order to identify one mushroom from the other? Focus on simple attributes like color, size, structure. Examples of questions include:
         1. "Is the mushroom X color?"
         2. "Does the mushroom have a cap with gills, pores, or teeth?"
         3. "Is the mushroom smaller than X?"
      3. Explain to learners that what they have done is created a simple dichotomous key for distinguishing these two mushrooms. Define dichotomous key.
3. Explain to learners that today they will be acting as true mycologists, focused on identifying some wild mushrooms. Although some of these mushrooms may look alike, they could end up being quite different! They will have to use real dichotomous keys used by real mycologists to try to identify their wild mushrooms as best as they can. In the process they will get to look at mushrooms up close under magnifying glasses or microscopes, and they may even have to make spore prints to identify their mushrooms! But before diving into identifying mushrooms, we have to talk about taxonomy and how these dichotomous keys work!
4. Introduce learners to the concept of taxonomic rank, which is the way scientists use to organize things. This short video may be helpful: https://www.youtube.com/watch?v=kKwOlAqQoLk
5. Explain to learners that fungi, like the mountain lion shown in the video, also belong to the Eukarya domain. Fungi are their own kingdom, like animals. From there, fungi fit into one of several phyla. For today's lesson we will only focus on two of these phyla - the basidiomycota and the ascomycota. The basidiomycota include all common club fungi - these are your typical mushrooms! The ascomycota include simpler fungi that are typically shaped like cups. Understanding these basic differences can help save a lot of time when using a dichotomous key, because we can usually tell what the domain, kingdom, and phylum of a fungus is just by looking at it! The dichotomous key then helps us narrow down what class, order, family, genus, and species a mushroom is. Identifying mushrooms down to species is very important when mushroom hunting, because some mushrooms can be very poisonous, whereas others can be delicious and edible!
   1. Be sure to include a disclaimer that learners should never consume a mushroom that they pick in the wild unless an expert has identified it, and even then wild mushrooms should never be eaten raw. Eating the wrong mushroom can make you sick, or worse (kill you), if you aren't careful!
6. To prepare the workspace for the lesson, cover each table surface with newspaper. This will help soak up moisture from the mushrooms and will catch any bugs that may be living or feasting on the mushrooms that will fall out when being handled.
7. Instruct the learners that they are to form groups (should be no more than 4 people per group).
   1. Recommend putting learners into groups by assigning them numbers and having the numbers group together.
8. Each group is to choose only one mushroom from the mushroom basket at a time to identify. Once they are done, if the mushroom is intact they can bring it back to the basket for another group to use.
9. Once a group has chosen their mushroom, they bring it back to their table and use the dichotomous keys in Mushrooms Demystified to begin identifying the mushroom down to phylum, class, order, and family. Once a group believes they have properly identified the mushroom at each stage, they must raise their hand and have the teacher verify their results. If a group is struggling to identify a taxonomic rank, it is okay to give them some gentle assistance by posing questions that will point them in a better direction. If a group has successfully identified their mushroom down to the family level or better, they may choose another mushroom.
10. Allow learners to work on identifying their mushrooms for ten or fifteen minutes.
11. At the end of the lesson instruct the groups to take two minutes to discuss with the intent to share:
    1. What did they learn from using the dichotomous keys?
    2. What did they find difficult about using the dichotomous keys?
    3. What mushrooms did they identify? How many basidiomycetes? How many ascomytetes? What were the defining characteristics of their mushrooms?
12. Ask each group to share their answers to the three questions. Be sure to probe each group to share the phyla and families of the mushrooms they identified, as well as the defining characteristics associated with each.

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References and resources

​Our lesson plans utilize the backward design model presented by Understanding by Design by Grant Wiggins and Jay McTighe

Mushroom identification information sourced from Mushrooms Demystified by David Arora

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