Students plant sunflower seeds in plastic cups, and once germinated, expose them to varying light or soil moisture conditions. They measure the seedlings' growth every few days using non-standard measurement (inch cubes). After a few weeks, they compare the growth of plants exposed to the different conditions and make comparative bar graphs that they analyze to draw conclusions about plant needs.
Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.
All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standard Network (ASN), a project of JES & Co. (www.jesandco.org).
In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.
Click on the standard groupings to explore this hierarchy as it applies to this document.
- Common Core State Standards for Mathematics: Math
- 4. Organize, represent, and interpret data with up to three categories; ask and answer questions about the total number of data points, how many in each category, and how many more or less are in one category than in another. (Grade 1)  ...show
- 1. Measure the length of an object by selecting and using appropriate tools such as rulers, yardsticks, meter sticks, and measuring tapes. (Grade 2)  ...show
- 3. Estimate lengths using units of inches, feet, centimeters, and meters. (Grade 2)  ...show
- 4. Measure to determine how much longer one object is than another, expressing the length difference in terms of a standard length unit. (Grade 2)  ...show
- 10. Draw a picture graph and a bar graph (with single-unit scale) to represent a data set with up to four categories. Solve simple put-together, take-apart, and compare problems using information presented in a bar graph. (Grade 2)  ...show
- International Technology and Engineering Educators Association: Technology
- B. Expressing ideas to others verbally and through sketches and models is an important part of the design process. (Grades 0 - 2)  ...show
- A. Asking questions and making observations helps a person to figure out how things work. (Grades 0 - 2)  ...show
- A. Discover how things work. (Grades 0 - 2)  ...show
- A. Collect information about everyday products and systems by asking questions. (Grades 0 - 2)  ...show
- A. Information is data that has been organized. (Grades 0 - 2)  ...show
- A. The use of technologies in agriculture makes it possible for food to be available year round and to conserve resources. (Grades 0 - 2)  ...show
- B. There are many different tools necessary to control and make up the parts of an ecosystem. (Grades 0 - 2)  ...show
- Next Generation Science Standards: Science
- Plan and conduct an investigation to determine if plants need sunlight and water to grow. (Grade 2)  ...show
- North Carolina: Science
- Summarize the basic needs of a variety of different plants (including air, water, nutrients, and light) for energy and growth. (Grade 1)  ...show
- Identify water, light and nutrients as needs of plants.
- Measure heights of objects using inch-cubes.
- Display data in the form of pictorial bar graphs.
- State conclusions drawn from bar graphs.
- 20 quarts (~22 liters) of good quality potting soil
- (optional) shallow plastic bins in which to place the potting soil for easier access
- sunflower seeds, enough for 2 per student plus 6 extras
- 20-oz disposable plastic drink cups, 2 per student plus 6 extras; punch holes in the cup bottoms in advance, as described in the Procedure section
- knife or scissors, to punch drainage holes in the cups
- permanent-ink marker
- plastic trays, enough to hold all the plastic cups
- 1" stacking cubes (Unifix cubes), 100 or more
- several liquid measuring cups with spouts
- several medium scoops, ~1 cup volume
- 1" grid paper, 3 sheets per student (1 for data graph, 1 for post-activity assessment graph, 1 cut up into squares)
- Drawing Handout, 1 per student
- data sheet, 2 per student (= 1 per plant); prepare in advance as described in the Procedure section
- data sheet, 1 per student, for a post-activity assessment activity
|The process by which a seed begins to develop into a plant.|
Before the Activity
- Gather materials and make copies of the Drawing Handout.
- Create and make copies of a simple datasheet for students to use. Provide lines for students to fill in the heights of their plants (in inch-cubes) on 8-10 different days. Also provide space for students to describe the experimental treatment for that plant, such as light and water, no water, no light.
- Prepare the cups for students: Use a knife blade or scissors to make a small hole (about 1 cm in diameter) in the bottom of each plastic cup, including the extra six cups Use a permanent-ink marker to draw a line around the inside circumference of each cup, about 1" below the top rim. Use the same marker to write each student's name on two cups, such that each student has two cups with his/her name on them.
- Prepare the extra six cups, which serve as backup plants that students can "adopt" later in the experiment if their own seeds fail to germinate. Fill each cup with soil, tamping it down lightly as you go. Using a measuring cup, determine how much water is needed to soak the soil in each cup. Add the water slowly, about a quarter of a cup at a time, until excess water begins to run out of the bottom of the cup. Make note of the average amount. Finally, in each cup press a seed into the soil to the depth stated in the package instructions. Cover the seeds lightly with some of the surrounding soil.
- (optional) To make it easier for students, use a marker or tape to show the target filling lines on the measuring cups.
- (optional) Place the potting soil into shallow bins for easier scooping access.
With the Students: Part 1---Introduction and Experiment Setup
- Administer the pre-activity drawing activity, as described in the Assessment section.
- Present the Introduction/Motivation section content to the class.
- Once the issues raised in the Introduction/Motivation section have been worked out, demonstrate how to fill the plastic cups with potting soil using scoops. Show students how to lightly tamp down the soil two or three times as they fill the cups. Demonstrate how to add water to soak the soil, using the amount you determined in advance. Also demonstrate how to place a seed in the center of the soil, at the depth stated in the seed planting instructions.
- After students finish the planting process, place all cups in the plastic trays (to catch drips). Place the trays in a bright location for germination, explaining that once the small plants appear, some will be moved to the dark place and others will not be watered. Point out that some seeds may be defective and won't germinate. Show students the extra cups you prepared earlier, and tell them that students can "adopt" these extras if their own seeds fail to germinate.
- Keep the soil in the cups moist, but not soggy, by watering when necessary. Demonstrate how to add water, again a little at a time, until it just begins to drip from the holes in the cup bottoms.
With the Students: Part 2---Running the Experiment
- Begin the experiment proper when enough seedling plants have developed so that each student can have two plants. The seedlings should be only an inch or two tall at this point. Begin by showing students the data sheets and explaining that every few days they will measure the plant heights using inch-cubes. Demonstrate how to do this with one plant and demonstrate how to record the measurement on the data sheet.
- After all students have measured their plants and recorded the heights, explain that half of the class will use one of their two plants to test for the effects of watering or not watering. Thus, this half of the class chooses one of their two plants to be deprived of water. The other half of the class will test for the effects of light versus no light. These students choose one of their two plants to be kept in a dark location, removing it only to measure it every few days and water it when needed.
- Determine which students will test for water/no water, and which will test for light/no light. Use a permanent marker to identify which cups will receive water and which will not, by drawing a large water droplet on the cups of those plants that are to be watered. Draw a water droplet that has been crossed out on the cups of the not-to-be-watered plants. Likewise, draw a sun or light bulb on the cups for plants left in the light, and the same symbol crossed out on cups to be left in the dark. Make sure students who are testing for light/no light know that both of their plants need to be kept moist. Also, make sure students label their data sheets appropriately, so that the plant measurements for each of their two plants match the treatment conditions for each.
- Ask students for predictions, as described in the Investigating Questions section.
- Have students observe and measure their plants every few days, recording their measurements on their corresponding data sheets. Prompt them to carefully observe the plants and document on their data sheets what they notice about the differences between their two plants, as well as the differences in other students' plant pairs. Ask questions that cause them to be specific and detailed about the comparative observations. Also ask them if what they are seeing is what they expected to see.
- Continue the experiment until the healthy plants are about a foot tall. Discard unhealthy plants and give the healthy ones to students to take home, or keep them in the classroom for further observation.
With the Students: Part 3---Graphing the Data
With the Students: Part 4---Analyzing the Data
- What do you notice?
- How do the graphs show the differences between the plants grown under different conditions?
- Which plants grew tallest? How do the graphs show that?
- Do the graphs show anything else about what the plants look like, for example, the color of the plants or the number of leaves they grew?
- What can you conclude from your experiment about what plants need to live and grow?
- If you want to advise someone who is going to plant sunflower seeds in a garden, what would you say?
- Do you think sunflowers would grow well in a forest? In a field? In a dry place, like the desert or under a car port where they get no rain?
- Think about some of the plants we see outdoors every day: What are the weather conditions like for these plants? Lots of sunshine? Is the weather often wet, or do long dry spells sometimes occur? What might happen to the plants that grow naturally in our region if we experienced a long drought?
- What differences do you expect to see in your two plants when you observe and measure them in a few days?
- Why do you think that will happen?
- Do you see any differences between your two plants?
- Are any differences you see a surprise to you? In other words, are you seeing what you expected to see?
Mary R. Hebrank, project and lesson/activity consultant
© 2013 by Regents of the University of Colorado; original © 2004 Duke University
Engineering K-PhD Program, Pratt School of Engineering, Duke University
Last modified: February 10, 2016