In later grades, students will learn that there are four essential components of natural selection — an important mechanism of evolution:

Variation: All life forms vary genetically within a population.

Inheritance: Genetic traits are inherited from parents and are passed on to offspring.

Selection: Organisms with traits that are favorable to their survival and reproduction are more likely to pass on their genes to the next generation.

Time: Evolutionary change can happen in a few generations, but major change, such as speciation, often takes many thousands of generations.

By the end of second grade, students should understand several of these components. They should understand that all individual living things have features that they inherit from their parents. However, offspring vary—they do not look exactly like their parents or exactly like one another. Usually, closely related individuals (e.g. brothers and sisters) resemble one another more than do distant relatives (e.g. cousins). This initial awareness of variation and inheritance will lay the foundation for understanding the process of natural selection later on.

In grades K-2, students should also be engaged in activities that help them to understand the nature and process of science. This will help them later on in differentiating between science and non-science. To find resources for teaching these topics, visit the grades K-2 teachers’ lounge on our sister site, Understanding Science.