Traits: Weigh the Evidence

Students revisit the two models presented at the beginning of the module. They consider how four lines of evidence relate to each model and explain why they think one is correct.

1. Distribute the Traits: Weigh the Evidence handout.
2. Share Evidence 1: Language(s) Spoken. Ask students if they think the trait come from genes or from the environment. If they decided it's only from the environment, show a clip from the How Traits Are Made video (just 1:29-1:46) to show that genes also play a role.
3. Model how to underline important information (see Tips from Teachers below) and fill in the table
   • If 3 lines of evidence is too many for your students to work with, distribute evidence cards among students or groups.
4. When everyone is finished, have students share their results with other groups or with the class. Make the point that when scientists evaluate models, they need to consider all the evidence—not just the evidence that fits their favorite model.
5. As a group, fill out the Whole Class Evidence table so that students can weigh all the evidence together. Discuss the statement at the top of the page about evidence that contradicts a model.
6. Hand back the Traits: Two Models copies that students completed at the beginning of the module. Have them fill out questions 3-5.

• As students read the evidence, have them underline information related to genes and circle information related to the environment.

• An organism's traits are the product of both genetic and environmental factors.

Copies

Traits Evidence (pdf)
Traits: Weigh the Evidence student sheet (pdf)
Whole-Class Evidence Table (pdf)

• Discuss what happens when you take organisms with the same genes and expose them to different environmental conditions. For example, identical twins have all the same gene versions but they are not exactly alike. And plants grown from a single potato are clones, but growing them in different conditions causes them to be different.
• Follow up with your favorite wet lab that illustrates how environmental conditions affect growth, or use one of these:
  • Hatch-a-cyst
  • Abuse-a-cyst

Eriksson, N., Wu, S., Do, C. B., Kiefer, A. K., Tung, J. Y., Mountain, J. L., & Francke, U. (2012). A genetic variant near olfactory receptor genes influences cilantro preference. Flavour, 1(1), 1-7.
Mauer, L., & El-Sohemy, A. (2012). Prevalence of cilantro (Coriandrum sativum) disliking among different ethnocultural groups. Flavour, 1(1), 1-5.
Saganová, M., Bokor, B., Stolárik, T., & Pavlovič, A. (2018). Regulation of enzyme activities in carnivorous pitcher plants of the genus Nepenthes. Planta, 248(2), 451-464.

The materials on this page are derivatives of the MEL Teaching Resources (accessed June 17, 2021), developed as part of The MEL Project by the Science Education Resource Center (SERC) at Carlton College, and licensed under Creative Commons Non-Commercial Share Alike 3.0.

Materials on this page are offered under a Creative Commons license Non-Commercial Share Alike 3.0.