Middle School Science Lessons

Objectives: students will learn to use a dichotomous key to identify unknown alien creatures.

Lesson Materials:

• Dichotomous Key – can you identify the aliens? (Google Doc, view only)
  • Original Lesson Plan from Biology Corner
  • Old handout (pdf)
• Alien Classification – Creepy Critters (pdf):  In this hands on lesson, students can practice sorting aliens and creating their own dichotomous key based on their characteristics.
  • The original website – Microbe World – no longer exists , this is a copy that I had saved.

How to use the key:

Students will start with Creature # 1 and work their way through the key until it has been identified. Starting with 1a and 1b, students will determine if the creature has the trait (yes) or does not have the trait (no) and follow the instructions stated to determine their next step. They will continue working their way through the  key using the creature’s characteristics until they have narrowed it down to only one possible answer.

Once they determine the Creature’s scientific name, they place the #1 next to the scientific name. Optional – they can write the name of the creature under the image of the creature, too. To continue, students will go back to creature #2 and work their way through the key again, and so on, until all 20 have been identified.

Using Creature #5 as an example:

• 1b) The creature has a small narrow head……………………..go to 11 (NO)
• 1a) The creature has a large wide head……………………….go to 2 (YES)

• 2a) It has 3 eyes …………………………………………go to 3 (YES)
• 2b) It has 2 eyes …………………………………………go to 7 (NO)

• 3a) There is a star in the middle of its chest………………..go to 4 (YES)
• 3b) There is no star in the middle of its chest ………………go to 6 (NO)

• 4a) The creature has hair spikes ……………………………Broadus hairus (YES) (#5)
• 4b) The creature has no hair spikes………………………….go to 5 (NO)