Unit B: Living Things and Where They Live

Why do you find seashells on the beach?

1. Get Set to Explore


  • parasite: An animal that lives in or on another living thing, called the host; the parasite harms the host.

Building Background

  • Introduce the topic of the simulation by suggesting that children recall or imagine walking along a beach. Ask them what they think they would see, hear, smell, and feel at the beach. For each thing they mention, have children classify it as a living or nonliving part of the environment. Write children's answers in a two-column chart on the board. Guide students to include wind and waves in the Nonliving column.
  • For each of the living things that children name, have them say whether the organism lives at the edge of the water, in the water, or elsewhere near the beach. Include this information in the chart on the board.
  • If possible, bring in shells of organisms that live in water and pass the shells around for children to examine. Ask children to describe what living things with shells are like.
  • Explain that, as children do the simulation, they will learn about many kinds of organisms that live along the seashore. Go over the vocabulary word, explaining that a parasite is a living thing that needs other living things to stay alive. Tell children: As you watch the simulation, think about what different living things get from each other.
  • Review the Discover! question: Why do you find seashells on the beach? Explain that the answer to the question relates to both the living and nonliving things that make up the ocean shore.

2. Guide the Exploration

  • Direct children to launch the Discover! Simulation. They should listen closely to the question and the directions.
  • Children should study the different living things in the ocean scene and move the cursor over each animal to learn more about it.
  • Encourage children to predict how the shell moves to the shore. Let volunteers share their predictions in small groups. Then have them click the Start button to watch the waves carry the shell to the shore. When the animation is over, they can replay the simulation.

3. Review/Assess

  • Go over Step 3's Wrap-Up text. Make sure that children understand that the animal that lived in the conch shell died. The water washed the soft body out of the shell, leaving the shell empty. Then, waves pushed the shell onto the beach.
  • Ask children to name the nonliving parts of the seashore that caused the seashell to end up on the beach. Refer children to the list on the board, made before they did the simulation. Guide them to realize that waves pushed the empty shell onto the beach.
  • Pose the Extension question. Review what living things need to survive: food, shelter, water, air, space. Have children return to the simulation and use the cursor to learn more about the living things in the picture. Guide children to note which animals need one of the other organisms for food and which use others for shelter. Following are examples:
    • The conch and the sea urchin eat grass and small plants.
    • The clam, oyster, and moon jellyfish eat tiny plants and animals floating in the water.
    • The horseshoe crab eats clams; the snail eats moon jellyfish.
    • The apple murex eats oysters; the bonefish eats shrimp.
    • The shrimp cleans parasites off the skin of some fish.
    • The oyster and clamshells provide homes for fish and crabs; they provide surfaces for sea urchins to attach to.

If time permits, present children with the following questions and activities:

  • Critical Thinking Apply How did the horseshoe crab, sea urchin, and snail end up on the beach? Answer: Like the conch, these animals have soft bodies in hard shells; after these animals die, waves push the empty shells onto the beach.
  • Inquiry Skill Work Together Work with one or two other children. Draw your own picture of living things in or near the ocean. Answer: Give each group a big sheet of paper, markers, and crayons. Have children talk in their groups about the living things they want to include; they can look for pictures in the science book or other books. With each group, make sure that everyone's best ideas are included and everyone gets to draw.

4. Reaching All Learners


Based on this simulation, children can make short food chains showing which animals eat other animals. They can write the name of different animals on strips of sticky tape and loop the strips to form a chain. Each chain should start with a plant or a plantlike organism that makes food. After children have two more links, challenge them to find out which animal eats the last animal in its chain and add it to their food chain.