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Science - 5th Grade
Standard 5 Objective 2
1 class periods of 60 minutes each
Students simulate natural selection. Colored chips are placed on a colorful habitat and student predators gobble up a portion of the population. Survivors will be allowed to reproduce and a new generation formed. Overtime it should be seen that those colored chips best adapted or blended into their environment will survive and reproduce. This will change the initial population to a new population better adapted to its environment.
Charles Darwin proposed the theory of Natural Selection in the mid 1800's. He studied many animal and plant populations along the coast of South America.
In his studies he summarized a list of observations.
Traits are passed down from parent to offspring through DNA. Sections of DNA that code for a particular trait are called genes. These genes can code for a variety of traits in the offspring. Genes that help an organism survive will allow the organism to reproduce and more offspring will carry the advantageous gene of the parents. Genes that hinder an organisms survival will reduce the ability of it to reproduce and then the gene will slowly become less prominent in the gene pool.
Darwin studied finches and observed that on each island the finchs food source was different. Over time, the finch population on each island changed and evolved towards successful adaptations to their food source. This occurred because the finches best adapted to their food source had their DNA more represented in the gene pool.
In this lab, color and its ability to blend into an environment is the trait that will be followed through three generations. As the abundance of each color changes within the three generations their population of color chips will change over time. This change in a population over time is called evolution.
1a. Observe simple objects, patterns, and events and report their observations.
1d. Compare things, processes, and events.
3a. Know and explain science information specified for the grade level.
4a. Record data accurately when given the appropriate form.
4b. Describe or explain observations carefully and report with pictures, sentences, and models.
6c. Science findings are based upon evidence.
Pre-lab discussion: Show the students a picture of Charles Darwin and discuss his life and journey on The Beagle. Display pictures of his finches and explain that due to the different food sources on the islands the finches had adapted to having different beak sizes and shapes. Ask the students what would happen if a finch that had evolved to eating soft worms off the ground had suddenly landed on an island where the food source was hard seeds and nuts. Perhaps that finch wouldnt be able to survive and reproduce and then its DNA wouldnt reoccur in the gene pool. Discuss how variation drives changes in populations. Tell the students that today they are going to simulate a population changing over time due to the variation in the offspring. Dont give away too much about the lab or students will begin to make sure that the lab works correctly.
** While student predators are waiting to eat, have them work on the Structure and Function of Bird Beaks worksheet.
** If 3 students pick up 25 chips each there should be 25 chips that remain on the fabric. These remaining chips on the fabric are your survivors.
Rio Tinto Hands-on Science Curriculum Team