Comparing Land and Water Plants
Life Science. Recommended for Grade 2.
Teacher Prep time: 15 min
Student Activity: 30 min outside for collecting plant samples
30 to 45 min activity time
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Essential Question
How are land and aquatic plants different? How are they alike?
Activity Objectives
- Describe how plants change to live in different habitats.
Next Generation Science Standards* (NGSS)
PE-2-LS4-1 Make observations of plants and animals to compare the diversity of life in different habitats.
Science and Engineering Practices
Planning and Carrying Out Investigations
- Make observations (firsthand or from media) to collect data which can be used to make comparisons.
Disciplinary Core Ideas
LS4.D Biodiversity and Humans
- There are many different kinds of living things in any area, and they exist in different places on land and in water.
Crosscutting Concepts
Patterns
- Scientists look for patterns and order when making observations about the world.
Safety & Disposal
Prior to taking students outside, locate an area where they can easily dig up a weed or small plant without harming school landscaped areas. Ensure that the terrestrial plants have roots, stems, and leaves after students dig them up. If the school grounds are not appropriate for plant samples, purchased plants like coleus, marigolds, and pansies work well.
To dispose of duckweed, place it in a resealable bag, freeze it for several days, and then dispose of the bag in the classroom trash. Do not dump duckweed into a body of water.
Procedures
- Cover the desk with newsprint.
- Have students remove soil from the plant roots before beginning.
- Add 2.5 mL of 2% sodium alginate solution to the tube, place the cap on the tube, and mix for 1 to 2 minutes.
- Collect some of the mixture into your pipet.
- Hold the pipet over a beaker containing 3% calcium chloride (CaCl2) solution. The calcium chloride solution should be cold.
- Prepare the CaCl2 solution a day prior to use and refrigerate it. Keep it cold throughout the procedure.
- Gently depress the bulb on your pipet to release the algae mixture drop by drop into the beaker. Do this slowly and uniformly. As the algae mixture drops in the calcium chloride, the algae will be immobilized inside of a bead. Your mixture should allow you to make approximately 100 algae beads.
- Make sure students are not squirting algae into the CaCl2 solution. Each drop should form a bead.
- Collect your beads using the plastic spoon provided and rinse them using the distilled water in the wash bottle.
- Transfer the beads to your clean culture tubes and fill the tubes with distilled water.
- Tightly wrap one tube with aluminum foil so no light can penetrate.
- Place the tubes in a well-lit area designated by your teacher.
- Use a light bank or lamp with a flexible neck. The light should remain on for the duration of observations.
- Observe the algae beads daily for 3 to 4 days. Rinse the tubes when finished.
- Observe the algae beads daily for 3 to 4 days. Rinse the tubes when finished.
Data and Observations
Look at the plants and fill in the data table.
| Land Plant | Aquatic Plant | |
|---|---|---|
| Shape of leaf | Will vary | Oval and thick or spongy |
| Number of leaves | Will vary | Probably 2 to 4 |
| Color of leaves | Green | Green |
| Where roots are attached | At the bottom of the stem | At the bottom of each leaf |
| Number or roots | Will vary | One per leaf |
| Color of roots | White to cream | White to cream |
| Shape of stem | Will vary | No stem visible |
| How leaves are attached to the stem | Attached by another short stem, the petiole | NA |
| Color of stem | May vary, usually green | NA |
| Shape of plant | Taller than broad | Broader than tall |
| Other observations | Will vary—students should note leaf veins | Will vary |
Analysis & Discussion
-
How are land plants and aquatic plants similar?
Answers will vary, but key points should include that they are both green and have leaves and roots. Both types of plants do produce flowers.
-
How are land plants and aquatic plants different?
Land plants have stems and a branched root system. Land plants are taller than they are wide. Aquatic plants have roots that hang into water. Each leaf has its own root. The leaves are thicker and somewhat spongy. There is no visible stem on the duckweed.
-
What makes land plants better able to live on land?
Branched roots hold the land plant in place and extend outward for water. Stems allow for more leaves, resulting in more photosynthesis and food for the plant. Broader and bigger leaves also allow for more photosynthesis.
-
What makes water plants better able to live in water?
Spongy leaves allow the aquatic plant to float on the surface of the water. Leaves are broad and flat so the plant can float. Aquatic plants don’t have to stay in place. Roots hang directly into water so they don’t have to branch.
*Next Generation Science Standards® is a registered trademark of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of, and do not endorse, these products.
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