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  • Date: Feb 27 2014
  • Author: Amy Balling
  • Category: STO Blog

What is it?: Dichotomous Keys

by Amy Balling,
Biology Teacher, Lancaster High School, Lancaster, NY

Dichotomous Keys photo 34Science Take Out’s What is it?: Dichotomous Keys kit is an easy to use way to help students understand the usefulness of dichotomous keys and to also give students the skills to create their own dichotomous keys. Most labs have one component or another but this lab kit has both.

The kit is easy to transport which makes it great for students on home instruction or in a location that does not have a proper laboratory setup such as a hospital, and is inexpensive and reusable. Many state education departments don’t allow students to complete online or virtual labs to meet their laboratory requirement and this lab is totally hands-on which allows students in a traditional classroom situation and students in an alternate location to complete a hands-on lab and to gain some important knowledge about dichotomous keys.

Dichotomous Keys photo 7I used this kit with my 9th grade biology students (1/2 inclusion) on a day after we discussed dichotomous keys in class. The kit includes laboratory handouts for students and a teacher set of instructions. Normally, when I order a ready-made lab kit from a company, I know I will eventually need to rework the handout or instructions to make it easy for my students to follow. That was definitely not the case with this kit. I could have removed it from the box, handed it to the students and said “go.” Looking back on it, I could have left this kit for a substitute teacher even if they weren’t science certified. It was that easy to follow. (But of course I wouldn’t have been able to get these pictures.)

My students were given a 40 minute class period to work through the lab in groups of two. The kit came with a set of really colorful plastic frogs and another set of plastic lizards. I know from watching my students use the kit that they loved the colorful frogs and lizards. It’s funny how a simple quality like bright color can persuade them to believe that it’s a fun lab. I actually numbered each bag and made the kids sign them out and back in because I was afraid that they would want to keep their favorite animal. Fortunately this didn’t happen.

The students worked through the identification of the frogs by following the instructions in the lab and the dichotomous key provided in the kit. Then they had to work together to create a lizard dichotomous key for a fictitious pet store. It was very interesting to see how each group could come up with an individual yet totally logical identification scheme for the lizards. My students were so fully engaged in following the lab that I was able to walk around and talk to each group about the characteristics that they used for their scheme. The students liked that the lizards fit on the paper flow chart of the dichotomous key included in the lab. It helped both the kinesthetic and visual learners who are commonly ignored in a traditional classroom.

Dichotomous Keys photo 20I could see this kit as a great introduction to the “Relationships and Biodiversity” lab that is required lab for students taking The Living Environment Course in New York State. Next year I would probably do this What is it?: Dichotomous Keys kit with my classes and have each group present their lizard dichotomous key to the entire class. The next day I would tell the students that scientists were able to do a DNA analysis of the lizards and I would give them fictitious DNA sequences and amino acid sequences of key proteins for these lizards. We would discuss that during the frog and lizard part of the kit we were looking at the structural characteristics of the organisms, but with molecular evidence our predictions could change. I would then have the students rework their dichotomous keys with the introduction of the new evidence (as scientists commonly do).

If you are looking for an easy way to introduce or review dichotomous keys with your middle school or high school science class or club, I would highly recommend ordering this easy to use kit!

Learn more about Amy Balling at http://about.me/amyballing
Follow Amy’s blog at http://ballinwithballing.blogspot.com