Beacon Lesson Plan Library

The Grass is Always Greener

Judy Marburger

Description

Students will use common grass to observe and experiment with cellular division.

Objectives

The student writes text, notes, outlines, comments, and observations that demonstrate comprehension of content and experiences from a variety of media.

The student understands that living things are composed of major systems that function in reproduction, growth, maintenance, and regulation.

The student knows that in multicellular organisms cells grow and divide to make more cells in order to form and repair various organs and tissues.

The student knows that accurate record keeping, openness, and replication are essential to maintaining an investigator's credibility with other scientists and society.

Materials

-Compound microscopes
-Onion root tip slides
-Student journals
-Potted grass plants
-Scissors
-Metric ruler
-Graph paper
-Access to resource materials
-Access to the video -Little Shop of Horrors-, directed by Frank Oz, starring Rick Moranis, Ellen Greene, rated PG13

Preparations

A discussion of cellular division and mitosis may be necessary prior to this activity.

A lesson on proper care and handling of the compound microscope is suggested prior to this activity.

Materials should be set up in advance so that groups may access microscopes and slides with limited classroom confusion.

This activity uses germinated grass seed. It will be necessary to prepare these prior to this activity. Each group of two will need three small containers of soil and germinating grass seed. It may be necessary to prepare these at least two weeks in advance.

This activity may be introduced and enhanced by using the video -Little Shop of Horrors-. This activity has been written using this video as an enhancement.

Procedures

1. Introduce the concept of cellular division using selected clips from the video-Little Shop of Horrors-, that show how the man-eating plant went through various stages of growth. Pose the following questions.
a. How do plants grow?
b. How do people grow?
c. Do you suppose there is a difference between how people grow and how plants grow? Explain.
d. What outside influences do you think might affect the growth of a plant? What outside influences might affect the growth of a person?
e. Have you ever heard,- Don't smoke, it will stunt your growth-? What do you think this statement means?

2. Divide students into groups of two for this activity. Have students observe the onion root tip on prepared slides. Explain that mitosis is occurring most rapidly at the root tip. Point out that root tips are specialized tissue in plants, as are stems, leaves, flowers, fruits, and seeds. Students should draw a picture and explain their observations in their journals. Have students address the following questions.
a. What is mitosis?
b. What are the stages of mitosis?

3. Give students three pots containing germinated grass seed. Have students measure the grass height in all three pots and record the data on the data chart (see Associated File).

4. Have students number the pots #1, #2, and #3. Have them cut the grass to half its height in pot #1 and to ground level in pot #2. The grass in pot #3 will not be cut at all. Pot #3 is the control.

5. Have students take daily measurements of the growth of the grass in all three pots and record the data in the chart. Students will make these observations and explain them in their journals for a period of one week. After two days of observations, have students answer the following questions.
a. How long will it take for the grass in pot #1, pot #2 and pot #3 to be equal in height?
b. In which pot do you suppose the grass will grow faster? Explain.
c. Do you think there will be a difference in the rate at which the grass grows in pots #1, #2, and #3?

6. At the end of a one or two week observation period, address the following questions.
a. Which grass grew the fastest?
b. Which grass grew the slowest?
c. How can you explain your observations?
d. How can you apply what you learned in your experiment?

7. Address all questions and observations. Post all data and discuss class results. Answer any questions and assess student understanding.

Enhancement:
How might the results of this experiment be used in the home or in the farming industry?

Assessments

The following questions may be used to assess understanding.

1. Which term is used for cellular division?
a. migration
b. separation
c. mitosis
d. glycolysis

(answer c: Mitosis is the term used for cellular division.)

2. In an experiment, cut grass is compared to uncut grass. Which of the following observations would you expect to be correct?
a. The cut grass grows faster.
b. There is no difference among the rates that the grasses grow.
c. The uncut grass grows faster.
d. None of the grass will grow.

(answer c: The uncut grass grows faster. It spends less energy repairing cellular damage and all division goes into plant growth.)

You may wish to assess students based on their laboratory activities. The following rubric may help.

3 points: The student has kept thorough, detailed observations of grass growth for five days in a journal. The journal writing is free of convention errors in mechanics, usage, punctuation, and spelling. The chart is accurate and neatly done; it addresses plant growth for five days for all three plants. The journal and chart have been completed and turned in on time.

2 points: The student has kept a journal of observations of grass growth for five days. The journal writing has some convention errors in mechanics, usage, punctuation, and spelling. A chart has been made that addresses plant growth for five days for three plants. There were some errors in accuracy. The journal and chart have been completed and turned in on time.

1 point: The student has kept a journal of observations of grass growth. A minimum of four days have been described. The journal writing has many convention errors in mechanics, usage, punctuation, and spelling. A chart has been created that addresses plant growth for a minimum of four days for three plants. There were many errors in accuracy. The journal and chart have been completed in a timely manner.

Self-Reflection:
What could be done to minimize or maximize plant growth?

Extensions

Students discuss:
How might the results of this experiment be used in the home or in the farming industry?

Attached Files

Chart to Record Growth     File Extension: pdf

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