Cuttings Lab
Summary:
In this seventh grade science lesson, students identify desirable traits in plants and take cuttings from parent plants to facilitate asexual propagation and produce offspring with identical DNA.
Student Learning Goals & Objectives:
After this lesson, students will be able to:
- Explain why plants are reproduced asexually
- Understand that asexual offspring are genetically identical to the mother plant
- Use cuttings to propagate perennial plants
Assessments:
During this lesson, students will:
- Identify three reasons for reproducing plants asexually in the garden
- Identify the cutting as genetically identical to the mother plant
- Successfully propagate a plant asexually
Materials & Prep:
Visual Aid
Wooden flat of growing medium (we use perlite)
Perennial plants with branches available for cutting
Examples of a rooted cutting and a mature, potted up cutting
Procedure Steps:
FULL GROUP, 5 MINUTES
1
AT THE OPENING CIRCLE
- Welcome students and introduce the Cuttings Lab.
- Explain that students will be rotating through the Cuttings Lab where they will learn how to generate more plants using asexual reproduction.
- Ask students what they already know about genetics and how traits are passed from generation to generation. Then ask students to share what they know about how plants typically reproduce.
- Explain that as gardeners, we often produce more plants by sowing seeds in the greenhouse and that the seed is the offspring of the plant. This is sexual reproduction.
- Explain that today, students will learn how to produce more plants through asexual reproduction and clone them rather than using seeds.
- Ask students what they think will happen to the DNA when the plants are cloned.
- Review garden jobs and closing circle activity: tasting.
- Divide students into 4 working groups, and explain that during their garden jobs, students will take a break to take an asexual cutting from a perennial plant.
SMALL GROUPS, 50 MINUTES
2
AT THE GREENHOUSE
- Students rotate from their garden jobs to the Cuttings Lab one group at a time.
- Gather students near the greenhouse and review that in this lab, they will learn one method of generating more plants through asexual reproduction with cuttings.
- Explain that a cutting refers to a small branch that we take from a mature plant and turn into a clone of the plant from which it was taken.
- Give examples of some of the traits you look for in a mother plant: fragrance, vigor, disease resistance, color of flower, etc.
- Reference the Visual Aid and explain the process while demonstrating each step.
- Show how to take the strike from the mother plant.
- Explain the importance of exposing the nodes.
- Trim the upper leaves.
- Place the cutting at a 45-degree angle in the growing medium.
- Prompt students to think about why it would benefit the grower to place the strike at an angle rather than straight down.
- Explain that we use perlite because it is sterile.
- Review what happens to the DNA of the cutting.
- Show students an example of a rooted cutting several months old and a mature, one year old potted up cutting.
- Ask students why a grower would choose to use asexual propagation. Discuss with students that there are three main reasons:
- It is faster than propagating by seed.
- You can select desirable traits.
- It is cost effective.
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Explain that students will walk through the garden and collect strikes from perennial plants to bring back and place in the tray of perlite.
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Have each student take a cutting of the perennial plant, expose the nodes and trim the upper leaves.
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Once all students have taken a cutting, have each one place their cutting in the wooden flat at a 45-degree angle, label it, and have one student water the flat when everyone is finished.
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As students are preparing their cuttings, ask them the following questions.
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Are these cuttings genetically identical to the mother plant? (yes!)
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Why is it important to expose the nodes? (from the nodes branches, leaves, or roots can grow).
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Why do we clip off the upper leaves on a cutting? (to minimize transpiration and help keep the plant moist)
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FULL GROUP, 15 MINUTES
3
AT THE CLOSING CIRCLE
- Have a few students serve a seasonal fruit, vegetable or herb tasting from the garden.
Downloads
Vocabulary:
Perennial
Cutting
Asexual reproduction
Traits
DNA
