Teaching materials : K-2 teachers' lounge :
Avoid common teaching pitfalls
Evolution itself may be too advanced for students in the lower grades; however this is the time to lay the groundwork for later learning with basic concepts like variation, inheritance, and the diverse traits different organisms use to make their livings. Unfortunately confusion and misconceptions that arise at this stage can plague students as they continue learning. You may wish to learn more about these misconceptions. Meanwhile, here are a few things you can do to avoid unintentional confusion when it comes to teaching your students the foundational concepts of evolution:
Choosing your words carefully: Function not purpose
The purpose of a hammer is to pound nails, and one's purpose in using the hammer might be to build a bench. However, it's not appropriate to say that one purpose of a hand is to hold a hammer. Instead, you can say that one function of a hand is to grasp or grip. Designed tools and independent agents have purposes. Structures of living things have functions. So, for example, it is preferable to say that the function (not purpose) of wings is flight or that wings are used for flying. Since purpose implies design or intent, this is an important distinction in the science classroom even early on.
Scientific terms that leave the wrong impression: Survival of the fittest
For many people, this phrase suggests that evolution only gives a pass to the best of the best. However, a better way of expressing how natural selection works is "survival of the fit enough." Portraying nature as a constant life-or-death struggle against competitors grossly oversimplifies what is really going on. Many life forms get by for eons by existing in niches for which other organisms are not suited or by simply being "good enough" to get their genes into the next generation. For example, brine shrimp live in water that is unsuitable for potential aquatic enemies, and they apparently have no significant competitors for food.
Learn more about misconceptions regarding adaptation and natural selection.
Slippery slopes in common classroom activities
Evolution is more difficult to observe than, for example, Newtonian physics. Thus, we often conduct activities in the classroom that are intended to be analogous to evolution and to the scientific enterprise. However, some of these activities can lead to misconceptions unless they are carefully planned.
A very common activity for young children is to have them make "fossils" by pressing shells into clay or plaster of Paris. While this clearly shows how a rock can contain molds and casts, it may well mislead children about the process by which fossils are formed in nature. In most cases, shell fossils are formed when shells are covered by sediment and over time the sediment hardens. This is very different from the process of squashing shells between two slabs of clay. If used with younger students, it is better to have students learn that you can identify what has left an imprint by looking closely at the imprint. And then if the students are old enough, a comparison can be made to studying fossil imprints.
Design an animal
When we ask students to design an animal to fit an ecosystem, on paper or out of pipe cleaners, we may be sending the message that living things are designed or that an individual animal can "adapt" to its environment by choosing to do so. This is far from the scientific view that living things are adapted over time to their environmental situations through genetic variation and natural selection. If you use such activities be sure to clarify for students how what they are doing contrasts with the natural processes of evolution.