Teacher: Christie Schneider
Class: Middle School Life Science
Date: November 22, 2005 thGrade Level: 7 Grade
Room Number: 164
Topic: Classification with dichotomous keys
Time: 15 minutes
; Instructional Goals and Rationale:
o 7.N.2.1. Students are able to conduct scientific investigations using given
; When viewing the dichotomous key, students are following a procedure
with only two steps to it. They will analyze the benefits of investigating
objects using the dichotomous key. The process is safe because the jelly
beans are contained in a plastic baggie for viewing. This prepares the
students for knowing how to follow processes and perform it in a safe way.
However, the students can eat the jelly beans if there is a problem with
identification of the flavor.
o 7.L.1.3. Students are able to classify organisms by using the currently recognized
; The students will learn about the classification system developed by
Linnaeus, binomial nomenclature, and apply it by using dichotomous keys
as practice. It helps them understand the origination of organisms by using
their scientific names, made from the genus and species category. This
will help them prepare for identifying organisms when using other tools
for identification in their later years.
o Cognitive –
; The students will recognize Linnaeus as the father of classification and
note that scientists still use his process for identification today.
; The students will understand what binomial nomenclature is and what a
dichotomous key is.
o Affective –
; As the students identify the jelly bean, it will help them know if they want
to eat that specific flavor of jelly bean or not. In the future, students will
come across jelly beans again and they might remember this lesson and
think about the coloration of the jelly bean before they eat it.
o Psychomotor –
; The students will conduct an activity to learn the process of how to use a
dichotomous key without having to worry about scientific names.
o Students will be sitting in their desks quietly and will have only a pencil out on
their desk in front of them.
o Hook Questions: ‘What things do you organize at home?’ Which will led us into
a review of classification, a scientific way to organize things.
o We will discuss briefly who the originator of classification was: Aristotle started
the idea, but more importantly Carolus Linnaeus, since he developed the process
of binomial nomenclature, a two-word naming system for identifying an organism
that scientists still use today. The reason for using Latin words is because of
language barriers. For example, a puma, cougar, and mountain lion are essentially
the same organisms, but depending where it is in the world, it gets a different
common name. Using the scientific name in Latin helps differentiate between two
similar organisms and gives less chance for confusion.
o We will then review the classification chart: kingdom, phylum, class, order,
family, genus, species. Have an example to look at: lion.
o Being able to use the chart can be helpful to know, but there are two tools to use
when identifying organisms: field guides and dichotomous keys. (Show examples
of both.) Today, we will be using a dichotomous key without using scientific
names, but will progress to it later in the week.
o From National Science Teachers Association (NSTA), I found a hand-out on
Harry Potter and the Dichotomous Key. I will go through the process of
describing what a dichotomous key is.
o I will then show them a few examples of dichotomous keys that other seventh
graders are using right now.
o Once they understand what it looks like and has an idea of what to do, I will spark
their interests even more by reading a section of Harry Potter and the Sorcerer’s
Stone to them (pp. 103-104).
o After that, I will have the 5 students split up into a group of 2 and a group of 3
and hand them a bag of jelly beans, a dichotomous key, and a paper to write their
discoveries on. They will be warned that these are indeed, Bertie Bott’s Every
Flavor Beans (show the box), so we might want to know what each bean is before
we taste it. (***note: these are actually Jelly Belly Jelly Beans, and all are safe to
eat; it is to keep the suspense in the activity.)
o I will let them know that I made a few changes to NSTA’s key because they were
not as specific as they should have been with the key. I will advise them to keep
the beans in the bag. However, if there is a discrepancy that comes up among
them, I will allow students to taste-test the beans, just to make sure their answers
o We will then go through one example together with the brown spotted jelly bean
and work through the process, being sure to write each step we go through: 1c,
24b, etc. so I know they are following the two-step (sometimes 3-5 steps,
depending on the options) process. Cappuccino jelly bean is our example. o After 3-5 minutes of using the key, they will notice they have 2 jelly beans that
are not on the key to identify. If time allows, they will create a two step process to
identify the two unknown jelly beans. They will have to taste test them to know
the difference and their choices will be between coconut and French vanilla. o At the end, we will discuss why it was a good idea to use the dichotomous key
first instead of eating the jelly bean without caution. Answer: So you know what
kind you will eat instead of getting an awful surprise! (Making a connection with
the affective objection.)
o It may look like you know your organism, but sometimes it is best to take the time
and research it first before you think you know the answer.
o For homework, they will get a handout to work on their own with a different
dichotomous key, but with animals they are familiar with. They will still need to
write down the process of how they get to their answer, and they need to write
down the scientific name next to the organism.
Posters – seven categories of classification and vocabulary
Examples of dichotomous keys
Harry Potter and the Sorcerer’s Stone book
1 box of Bertie Bott’s Every Flavor Beans
Baggie with 15 assorted jelly beans
Jelly Bean Dichotomous key/ worksheet