Lesson 2: Seed Germination
(45 minutes, with follow-up observations for 3-5 days, and 45 minutes on final day)
Key question: How does a seed germinate?
- Students will plan and conduct an investigation to determine the best germinating conditions for corn seeds.
- Students will observe and record data (drawings and descriptions) while seeds are germinating.
- Students will analyze their recorded data, labeling structures they observe and indicating functions for them.
- Corn seeds in 2 plastic baggies, prepared a day or two in advance with one having a little water added, and the other that is dry.
- Additional dry seeds
- Baggies for students
- Water and a variety of other liquids such as orange juice, soda, energy drink, vinegar, oil, milk, baking soda water
- Sharpies for labeling
- Science notebooks with seed growth journal
- Colored pencils
- Magnifying glasses
- Corn seed germination diagram with labeled structures
Procedures for Instruction
If your students utilize science notebooks, print out the notebook pages provided in lesson 1. 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.
Day 1 (45 minutes)
Introduce the topic and assess prior understanding
- Present the 2 bags of seeds to students, one that had a little water added a day or two ago, and one that is dry.
- Tell students that you aren’t sure what happened to the seeds: “Look what I found! Here are 2 bags of seeds. They look like they’re left over from when we planted our seeds three weeks ago!”
- Don’t tell the students that one has water in it – let them discover this on their own. Pass the bags around.
- “What do you see?”
- “What do you think happened?”
- “They look different – I wonder why?”
Record their thinking in their science notebook, and discuss as a class to assess their thinking.
Do not signal right or wrong answers. Just let them discuss their ideas, and guide the flow with such prompts as:
- “Can you say more about that?”
- “Why do you think that?”
- “Who agrees/disagrees with this idea and why?”
- “Does anyone have a different idea?”
- “Would this be true all the time?”
Develop an investigation as a whole class or in small groups
Develop an investigation as a whole class or in small groups based on the question, “How does a seed germinate?” Hand out corn seeds and baggies, letting students figure out that they will be placing a few seeds in each baggie, and seeing if they will germinate in different conditions. Have a variety of liquids setting out. Guide the development of the investigation with such questions as:
- “What does a seed need to germinate?” (Based on the introductory activity, they should realize it needs water. If not, guide them to reflect on the introductory activity to understand this.)
- “Does it have to be water, or can it be any liquid? Does it have to be a liquid?”
- “Which liquid will work best? Why?”
- “Should the bag be opened or closed? Why?”
Focus the elements of their investigations
- “What is our research question or questions?” Have students generate their own questions about the seeds, and possibly set up different observation stations around the room for different questions. Write the questions on the board or anchor chart.
- “What kind of data do we need to collect to show what we know?” (Introduce seed germination journal, and how they will observe, draw, and write in their science notebook.)
- “What are the different conditions (variables) you want to test?” Let the students pick the different kinds of liquids they would like to test.
- “Should we have something to compare to? Would the seeds just have germinated anyway? Should we set up comparison baggies (controls) using no water, and just water?”
- “What do you think will happen and why in each condition?” Have them record this as a prediction or hypothesis.
Instruct students to set up the investigation.
- Guide students to prepare their baggies and seeds according to their own questions.
- Using sharpies, have them label their baggies with their name and conditions.
- Have them record the set-up of their investigation, including research question(s), type of data they will need to collect, different conditions (variables), what they will compare the experimental conditions to (controls), and predictions/hypotheses.
Record their observations in their science notebooks by drawing and writing.
- Use colored pencils and magnifying glasses.
- Each day for 3-5 days, have students observe the progress of the germinating seeds and record their data. Be sure they draw and write in their science notebooks what they see happening with the corn seeds in their baggies.
Final Day (45 minutes)
Discuss their findings by having students share results.
You can do this as a large group, making note of their findings on an anchor chart or on the board, OR you can split them into small groups to compare their findings and report out. Lead the discussion with such questions as:
- “The corn seeds germinated best in which conditions?”
- “How did the various liquids compare to our control conditions (water and dry)?”
- “Why do you think you got the results you did?”
- “Were there any contradictory results?”
- “What new questions do you have based on your findings?”
- “Based on your evidence, how do you think a corn seed germinates?”
- “Do you think this is true of all seeds? How could we find out?”
Explore seed and sprouting seed structures
Ask students to examine their drawings from the different days again, and
- Label the different structures they drew or wrote about. Do not give them the “proper” terms for the structures – let them use their own descriptive words.
- Then have them suggest functions for each structure – again, do not signal if they are correct or not, but have them justify why they think that. Encourage their thinking.
- Discuss these structures in a large group with having students share their labeled structures and proposed functions.
Explain how their discoveries are very much like those of scientists’ discoveries.
- “You planned and conducted an investigation to determine how corn seeds germinate, and you have formed conclusions based on very convincing evidence! You are budding scientists!
- “You observed carefully and identified parts of the seeds, and proposed functions for them. You are certainly budding scientists, because that’s what many plant scientists do – they observe carefully and identify structures on plants that many people never even knew were there! If those structures have no names, they have to name them. They also observe very carefully over time to see what functions those structures have.
- “Let’s look at what scientists have named the structures you identified, and what they have found are their functions.”
Show a diagram (model) of corn seed germination, with major structures labeled.
Parts of an Emerging Seed- No Words
Parts of an Emerging Seed- Words
Emerging Corn Plant Structures and Functions
- Distribute copies of diagrams to students and have them label the structures as you guide them.
- Have them compare their terms for each structure to the term scientists use.
- If they have room, they can label their own drawings with the scientific terms.
- Discuss the function of each structure.
- “Were you surprised to discover so much going on in the seed as you observed them germinating?”
- “What do you wonder about now?” (Guide them to connect the seed germination they have observed to the seed germination that occurred in the soil of the plants growing in the classroom, AND the plants growing in corn fields throughout the world. In fact, all seeds of plants germinate in similar ways – this is happening underground all over the world!)
- Show the time lapse video of corn growth called, “Time lapse fast growing corn, roots, and leaves growing” found at https://youtu.be/iFCdAgeMGOA
- Assess contributions in discussions for prior understanding and adjust instruction if needed.
- Assess their observation and recording skills as they draw and write in their science notebooks. If needed, encourage them to look closer, to notice things with the magnifying glasses that are slightly hidden (are they seeing all the root hairs, for instance?).
- Science Notebook observations
- Corn Seed Germination diagram, labeled with structures and functions
Extra Information for the Teacher
A seed is the house for a future plant, outfitted to furnish what a baby plant needs to start to grow and succeed in life. A seed is wrapped in a tough outer coating (seed coat) that prevents the future plant from damage. Inside, there is a food supply and the beginnings of a new plant. In the world of flowering plants, there are monocots and dicots. A monocot seed has an embryo that contains one cotyledon, the part of the plant that becomes its first leaf-like structures. A dicot seed has an embryo with two cotyledons. The cotyledons help provide and absorb nutrients for the plant until the plant is ready to make its own food through photosynthesis. Corn kernels are monocots, and beans are dicots.
Inside a corn kernel (seed), there is a cotyledon near the bottom, pointy part of the kernel, where the new plant begins to grow. It is surrounded by the endosperm, which is starchy food for the baby plant. When the seed begins to grow, its protective covering breaks open in two places. The top breaks open to reveal the coleoptile and eventually the plumule, the future shoot of the plant. The bottom breaks open to reveal the coleorhiza and eventually the radicle, the future root of the plant.
Like the corn seed, the bean seed has places where the root and the leaves emerge. However, since bean seeds are dicots, when you open one up, you’ll see it has two cotyledons that look like reverse copies of each other. Instead of having a separate baby plant and food supply,
inside the bean plant the cotyledons contain the endosperm (the food supply).
As the root grows, tiny little root hairs extend out to form a net-like mass to absorb water at a microscopic level. Guide students to look for these and all the structures using magnifying lenses.