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
- Cactus/ Cacti
-
Succulent
-
Desert
-
Comparative study
Objectives
- Students will apply what they’ve learned about cacti by interacting
with the prickly plants directly.
-
Students will learn how to conduct a comparative study in order to
learn more about a particular type of organism.
Next Generation Science
Standards
-
LS1.A-B. Structure and Function; Growth and Development of Organisms
-
LS2.A. Interdependent Relationships in Ecosystems
-
LS3.A-B. Inheritance of Traits; Variation of Traits
-
LS4.B. Natural Selection
-
LS4.D. Biodiversity and Humans
-
PS1-6. Asking Questions; Planning and Carrying Out Investigations;
Obtaining, Evaluating, and Communicating Information
Required Project
Materials
- If possible, a visiting botanist
-
A few potted cacti
-
A few potted plants of various types, for comparison purposes (if
possible, include non- prickly kinds of succulents as well)
-
Magnifying glass
-
Sketch pad, pencils, and erasers
Multimedia Resources
- Cactus Hotel. Brenda Z. Guiberson and Megan Lloyd.
http://amzn.com/0805029605
-
Mac’s Field Guide to Cacti and Common Trees and Shrubs of the
Southwest. Macgowen.
http://amzn.com/0898862957
Optional Multimedia
Resources
- Animals Up Close . Igor Siwanowicz.
http://amzn.com/0756645131
Before the Lesson/ Background
Information
- If possible, locate a botanist or biologist to come help guide the
lesson.
Homework from Previous
Session:
The Lesson
Part 1: The Cactus (15
mins)
- Read Cactus Hotel with the students.
-
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)
- If a botanist is assisting with the lesson, have him or her conduct a
short presentation about cacti.
-
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.
-
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.
-
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.
-
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.
-
Have the students go through the same process with another plant (one
of the non-cactus varieties).
-
Ask the students to compare and contrast the cactus with the other
plants based on their observations. What did they learn?
-
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.