Prickly Plants: the Capable Cactus

Suggested Time: 60 minutes
Overview
Students will learn about cacti, including why they have prickles, and why they are important in the environments where they live. Students will also learn about how plants and animals defend themselves in the wild. Finally, they will conduct a comparative study and come up with their own data and results about how cacti compare with other kinds of plants.
Vocabulary
Objectives
Next Generation Science Standards
Required Project Materials
Multimedia Resources
Optional Multimedia Resources
Before the Lesson/ Background Information
Homework from Previous Session:
The Lesson
Part 1: The Cactus (15 mins)
  1. Read Cactus Hotel with the students.
  2. Ask the students to think about why most cacti have prickles. What are some other tools or traits animals and plants use to defend themselves?
Part 2: Comparative Study (30-45 mins)
  1. If a botanist is assisting with the lesson, have him or her conduct a short presentation about cacti.
  2. As an individual or group exercise, have the students carefully examine the features of each cactus. They should both observe the cactus and use the magnifying glass.
  3. Students should sketch the cactus, paying close attention to the shapes of the leaves and any features like buds. If applicable, make sure they label the drawing with the features of the plant.
  4. Have the students use Mac’s Field Guide to try to identify the plant. They should write the scientific and common name (or their best guess) on the top of the sketch.
  5. On the sketch, have them draw a box or circle to the side or in the corner of the page. Here, they should draw what they saw under the magnifying glass.
  6. Have the students go through the same process with another plant (one of the non-cactus varieties).
  7. Ask the students to compare and contrast the cactus with the other plants based on their observations. What did they learn?
  8. Let the students know that they just conducted a “comparative study”, which is a type of research that involves comparing different objects and drawing conclusions from the observations.