The Sloth Has a Secret Lesson Plan

Academic Standards


Reading Objective:

Children will understand how sloths, moths, and algae form an ecosystem.


Reading Level:

Lexile: 510L; GRL: L


Next Generation Science Standards:

2-LS2 Interdependent relationships in ecosystems



mammal, algae, nutrients, absorb, ecosystem

Use these questions to check students’ understanding and stimulate discussion:


1. What are two ways that algae helps the sloth? (Eating algae gives the sloth energy, and its green color lets the sloth hide in the green treetops.)

2. What helps keep the algae alive?
(Moths that live in the sloth’s fur. Their bodies provide nutrients.)

3. How does the sloth help the moths? (It climbs down to poop, so moths can lay eggs.)

4. If you were a sloth, would you want green algae on your fur?
(Yes. It would help you hide from danger in the leaves.)

Go online to print or project the Reading Checkpoint.


  • Sloths live mostly in South and Central America.
  • They sleep for about 15 hours a day.
  • When sloths poop, they poop a lot! They can lose a whole third of their body weight.

Materials: pencils, copies of the skill sheet, watch or smartphone to time kids

Overview: Kids will practice science skills of recording and comparing as they get moving.


  1. Remind children that sloths move slowly. Sloths do it to save energy, so their bodies don’t have to work so hard.
  2. Go outside or make space inside to run in place. (Or have kids do this remotely.) Pass out the skill sheets.
  3. Tell kids they will run in place, then count their heartbeats. More heartbeats mean the body is using more energy. Then they’ll move slowly and count again. Predict which will make the heart beat more.
  4. Time to move! Let kids run, then stop and check their pulse. To do this, they can hold three fingers to their Adam’s apple and press gently on one side. Let them feel and count their heartbeats for 10 seconds. Record results on the skill sheet. Then let kids walk slowly, and check pulses again.
  5. If time allows, have a sloth race. The last kid to finish wins!