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Earthworm Dissection (Grades 9-12)

Master Teacher

David Banaszak

Overview

This lesson focuses on how students can suc-cessfully dissect an earthworm. It will be broken up into two lessons—external and internal examination. This lesson focuses on external examination.

ITV Series

Earthworm Dissection, Lesson #1

Learning Objective

Students will be able to:

identify the external features of the earthworm

Materials

preserved earthworms
dissection trays

Previewing Activities

1. Have students measure a 5' x 5' section of their front or back yard. Tell them to soak the ground in this area towards evening. Then they should count the number of earthworms they see in this section.

At school, explain to them that these earth- worms are all over the world. They're not only for fishing, but they also serve useful purposes such as food for animals and helping plants grow by loosening the soil and providing useful nutrients for them.

SC Math/Science Standards Met

Science Achievement Standards

Process Skills—A
Area I—Living Things
Strand 1: D

Focus for Viewing

Tell students to look for the external structures of the earthworm in the video. Pass out dissection trays and preserved earthworms. Say, "Before we do anything to these earthworms, let's look at their external structure."

Viewing Activities

Start the videotape at its beginning and play until you hear "soft moist soil." Ask where earthworms can be found.

Resume the video until you hear "external skeleton." Ask why earthworms are easy to dissect. Ask what life functions earthworms perform—listen to student answers.

Tell the class, "Let's see.…" Start the tape and stop when "circulation, digestion, respiration, reproduction" are all on the screen. Discuss students' earlier answers.

Play the tape until you hear "particular environment." Say, "Let's look at these differences on our worms while the narrator explains them." Play the tape, stopping after each example. Give students time to find these features on their own worms. At "mouth," freeze frame and have students find their worms' mouths. Check to see that everyone found theirs. Play the tape; at "anus" freeze frame and have students finds their worms' anuses. Have students compare the TV image with their worms. Start the tape; at "blood vessel" freeze frame and have students find their worms' dorsal blood vessels. Check students to make sure they can see their worms' features compared to what's on the screen. Play the tape; at "clitellum" freeze frame and have students find the clitellum of their worms. Compare to TV.

Start the tape and have students follow the examples on TV—"feel the worm," etc.… At "setae," have students feel the worms' bris-tles—make sure everyone can feel them. After examining the worms, students should label the diagram of the worm. (See Activity 1.)

Play the first nine minutes of the tape again so students can use it to help them identify worm structures on their diagram.

Post-Viewing Activity

1. Have students look up annelids on the Internet. Using information from the Internet, compare/contrast the earthworm with another annelid.

Possible Internet sites:

Action Plan

1. Students can investigate different areas a-round their neighborhoods to find as many types of annelids as they can.

2. Compare/contrast with earthworms they dissected—externally and internally.

Extensions

1. Math: Have students take the information from the previewing activity (counting the number of worms in a five-foot-square section of their yards at home) and have them find out how many earthworms are on their entire property.

2. Art: Students can make posters illustrating the external structures of the annelids they found on the Internet. Label each part.

3. Social Studies: Students can find where the 10-foot worms are and make a map of the area.

Activity Sheets (PDF)

Activity Sheet 1