Natural selection. Survival of the fittest. Evolution. You’ve been hearing those terms a lot during your school years. But, what do they really mean? The activities in this lesson will help you begin to understand evolution and the mechanisms that help to drive it.
Watch the movie Natural Selection at the BrainPop website then answer these questions in your science notebook.
- How does natural selection work?
- What did Darwin study to learn about natural selection?
- What is a species?
- How does a new species come into being?
- What happens after long periods of natural selection?
Now you will engage in an interactive activity in which you will be able to observe the process of natural selection by changing the amount of pollution in an environment (i.e., the background color of the screen) and then observing its effects on the survival of green and orange bugs.
- Go to Nowhere to Hide to play the online interactive activity about natural selection.
- Click the "How to Play" button on the bottom left of the screen. Scroll down using the arrow key to read all of the instructions for the game.
- Now click the "Back" button to go back to the game and begin the online interactive. Remember, the goal of this activity is to observe what happens to the bugs (green and orange) in response to an increase or decrease in pollution levels (the color of the background). The pollution level can be altered by dragging the slider either towards the orange factory (more pollution) or towards the green trees (less pollution).
- Once you are finished playing the game, click on the "Learn More" button to read about the science and history behind the game.
- Then click "Done" and return to the esheet.
Answer these questions based on the knowledge you gained from playing the interactive and from reading the "Learn More" section.
- Which bugs (orange or green) were eaten more when there was a low level of pollution (background green)?
- Which bugs (orange or green) were eaten more when there was a high level of pollution (background orange)?
- What factor determined the survival of the bug? Why?
- If the pollution level is high for an extended period of time, does this affect the survival of the green bugs? Yes or No.
- Would they increase or decrease over time?
- If the pollution level is low for an extended period of time, does this affect the survival of the orange bugs? Yes or No.
- Would they increase or decrease?
- In natural selection, the organisms that are best suited to survive in an environment have the most babies and grow in numbers, while organisms that aren't as well suited to the environment shrink and disappear. True or False.
- Do you think this process occurs over a short period of time or a long period of time?
The main point of this lesson is to understand the concept of natural selection including the meaning “survival of the fittest.” Get together in groups (no more than four) and come up with an explanation of natural selection and what “survival of the fittest” means. You will have five to ten minutes to do this activity. Be ready to share the answer you had before and after you did this lesson.
After the answers are shared with the class, your teacher will give you the definition of the term natural selection obtained from the Frequently Asked Questions About Evolution page on the PBS Evolution site.
Once you have heard the definition for natural selection, come up with another activity that would demonstrate the process of natural selection. (Reminder: The one in the online activity used pollution [background color] and different colored bugs.) What other scenario could you create and how would it work (e.g., birds have different beaks depending upon the type of food they eat—cactus finches have long beaks, ground finches have short beaks, and tree finches have parrot-shaped beaks)?
Information about these birds can be found on the Natural Selection in Real Time website.
This esheet is a part of the Nowhere to Hide lesson.