Lesson 2: Planting Seeds
(30-40 minutes, with follow-up observations for 7-28 days)
Key question: How can we prove that a corn seed does or does not need soil, water, and sunlight to germinate and grow?
- Students will plan and conduct an investigation to understand what corn needs in its habitat to survive well.
- Students will make observations and record their findings to construct an evidence-based account that corn needs water and sunlight to germinate and grow.
- Science Journal, Journal page inserts (“Corn Plant Growth,” “Science is All about,” and “Corn Plant Growth Data” sheets)
- Glue sticks
- Corn seeds
- Planting pots
- Soil (and other materials such as sand, rocks)
- Balance scale and gram pieces to measure soil/other material amounts
- Water (and possibly other liquids)
- Label Sticks
- Liquid measuring tool such as beaker, graduated cylinder, syringe
- Grow light (if available) or basin to set pots by a window
Procedures for Instruction
If your students utilize science notebooks, print out the notebook pages and have students cut and paste the pages into their notebooks. If your class does not use specific science notebooks, consider makings ones by copying and stapling together pages to create science notebook for your students.
Journal page inserts
Introduce the topic and activate prior learning
- “How can we prove that a corn seed does or does not need soil, water, and sunlight to germinate and grow?”
- Post this question in the classroom for reference throughout the investigation.
Once students realize they need to develop an investigation, proceed to get out science journals
Work together as a class to develop answers to the following questions. Using the Teacher Science Journal, and projecting it through the document camera, develop the ideas, and model what they should record in their journals.
- “What steps can we take to create and plan an investigation to test our ideas?” Have students record this in their journals, and number each step.
- “What conditions will we be testing?” (growing plants in dark vs. light; with water vs. no water or another liquid; in soil vs. a damp paper towel; etc.)
- “What materials do we need to conduct this investigation?” Have students record this in their journals. Display the actual items (planting pots, soil, corn seeds, etc.). Showing the students will help them if they do not have any background knowledge. Draw and label the materials.
- “How long will we need to grow?”
(Note: Optimum planting depth of corn kernel in soil is 1-2 inches deep. Emergence of leaf above the soil will take approximately 5-7 days. Additional days or weeks may be desirable.)
Small group planning and investigating
- Place students in teams of 4-5 for conducting the investigations.
- Instruct students to decide among themselves their investigative roles:
- What conditions will each student plant their seeds in? (One student will plant seeds that will grow in dark, one that will grow in light, one that will be given water, another a different liquid, etc.)
- Have students follow their own steps to start their investigations, which might include planting seeds, or placing young plants in different growing conditions (See “Corn Plant Growth” sheet).
- Using the label sticks be sure to label planting containers with student names. If students have more than one planting container, they should number them so they know which plant goes in which growing condition, and record this in their journal. (This may seem unnecessary, but when they observe the pots to record data, the containers may get switched.)
- Guide students in how to use measurement tools correctly, and emphasize the importance of keeping amounts constant so they can conduct a fair test among the conditions.
Planning and conducting observations as a whole class
- Add data collection recording pages to the students’ journals.
- Discuss what makes good quality data collection (See “Science is All about” sheet):
- Observing details (What do they see? What can they measure? What has changed? Anything surprising?)
- Record accurate details
- Draw and describe with words
- Observe and record what they did today (See “Corn Plant Growth Data” sheet).
- Set up a schedule for the duration of the investigation (7-28 days) for students to make and record observations (collect data). Observations can be made every few days in the “Corn Plant Growth Data” sheets of student science journals.
Note: Determine how many times you want students to observe plants and record findings, and be sure to provide enough data sheets in their journals.
Observe and record results over 7-28 days
- Have students water the soil as appropriate over the next 7-28 days.
- Provide brief (3-5 minute) observation times during those days / weeks for students to observe (draw) and record (describe) in their science journals the progress (or lack thereof) of their plants.
Prompt students to collect data, make accurate observations, and record the data in their journals. Keep wonder alive by showing deep interest in their observations, asking them what they have found, what data they are collecting, and if they have any preliminary thoughts based on their evidence? Refer back to the investigation question posted in the classroom: “How can we prove that a corn seed does or does not need soil, water, and sunlight to germinate and grow?” Ask if they think they are gathering evidence to answer this question.
Assess students’ understanding of plant needs based on their propositions of how to plan and conduct an investigation. Adjust instruction and prompts accordingly.
Assess student plans and observations as recorded in their Science Journals. Are the plans and data collection clear and detailed? Do the plans provide fair tests for the conditions they are testing?
Background information for teachers
Seeds do not need soil to germinate. Soil is a substrate that holds water that the seed needs to germinate. Once the plant reaches sunlight, it will start photosynthesizing, creating glucose and plant matter which results in growth. The soil is necessary only to hold the water it needs, to provide tiny amounts of micronutrients it needs, and to provide structure to support a standing plant. It technically does not need soil to survive and grow. A seed also does not need sunlight to germinate. The seedling can grow quite substantially as it tries to reach sunlight, but ultimately it will not be able to photosynthesize without light, and so will not survive long if it does not find light.