SUMMARY: This is a lesson on the initial growth of a seed. The three main parts of a seed will be discussed and explored, as well as the part they play in the seeds growth and development.
GRADE LEVEL: third grade
In the Alabama Course of Study, this topic would go under #32 for third grade--"Classify plants and animals according to their features," in this case physical.
Seeds have a seed coat which protects them while they grow and develop, usually underground. Inside the seed there are is an embryo (the baby plant) and cotyledons. When the seed begins to grow, one part of the embryo becomes the plant while the other part becomes the root of the plant. Food for the plant is stored in the cotyledons. Some seeds when split apart seperate into two halves. These seeds have two cotyledons and are hence called dicotyledons. Other seeds have only one single unit, with only one cotyledon. These are called monocotyledon seeds.
The "baby" plant grows entirely from stored energy and food from the cotyledons until it reaches sunlight. The food supply in the seed will last up to about two weeks. As the seed develops, the embryo always grows upward, and the root always grows downward. Even when the seedlling is turned upsidedown, the plant will right itself. All of this is due to the gravitational pull of the Earth.
Seeds need a certain amount of water to grow. However, too much water is detremential. Seeds also need oxygen and the right minerals from the soil. They do not, however, need light to grow. In fact, they often grow faster in the dark.
Seeds have a small hole on the outside that lets liquids such a water in. This hole is the point at which the seed was joined to its pod. The pod fed nutrients for the cotyledons through this hole.
- seeds expand when soaked
- a seed's coat is hard and tough when dry, but soft and easy to remove when wet.
- a seed is made up of three main parts:
(a) seed coat
(b) embryo (baby plant)
(c) food source ( cotyledons)
- seeds live off of the food they have stored inside until the point when they reach the sunlight
large lima beans
"Inside of a Seed" diagram worksheets for each student
red kidney beans
Begin by choosing one student to pass out the dry beans, one per student, and one student to pass out paper towels to each student. Then place a cup full of water containing the wet lima bean in front of each student.
Have students remove the wet lima bean from the cup and place on the paper towel. Have them compare the visual differences in the two beans. Make a chart on the board labeled "WET" and "DRY," and list the differences given by the students as a group.
Q: Why is the wet one bigger?
Q: How did the water get into the seed if it has a hard coat? Can you find a hole on the seed?
Q: Is the inside of a seed empty? If not, what is inside?
*Make a chart labeled "What's Inside a Seed" and have students offer their guesses to the above question.
Q: How can we find out for sure?
Instruct students to carefully split open the wet seed into two parts and place on the paper towel.
While they are doing this, pass out the diagrams of "The Inside of a Seed" and assist students when needed.
Have students compare the inside of their seed to the diagram on the worksheet. Have them identify the seed coat, embryo, and food storage area in their seed. Have them remove the seed coat, if they have not already done so, so they can see that it is a seperate "coat."
Explain how the embryo is the baby plant and how it will grow into the developed plant.
Q: Do you see the shape of the future leaves in your seed?
Q: What part makes up most of the inside of the seed? Why do you think this is so?
Explain how the seed uses the food as its only supply until it reaches sunlight.
Show students bean sprouts to explain how baby plant grows.
Q: Do all seeds have the same insides? How can we find out?
Allow students to follow the same procedures above using different kinds of seeds.
Prepare a chart comparing different seeds.
Drama Activity: Have students decide how to divide up the student to create one whole seed from the whole class. Some will be the embryo, and some will be the food source. (Assume there is a seed coat surrounding the group). Have students gather in the back of the room to form their "seed." Indicate the passage of two weeks, allowing students to demonstrate what happens inside the seed as it deveops over this period of time. By the end of the two weeks, most of the students who were food sources should have converted to baby plants.
I plan to assess the students' knowledge of the three parts of a seed by having them label a blank diagram of a seed, adapted from the handout.
To asses their understanding of how the food is used in the seed, I plan to observe the whole class in the presentation of the "I'm a Seed" drama activity.
Reflection of Lesson 1: The Inside of a Seed
I really felt that today's science lesson on seeds went really well. I was on such a high for the rest of the day because this was my first experience teaching a whole class. I was very pleased with the way the lesson turned out. The students reacted in about the way I expected them to act, and asked all of the right questions. I suppose that was my biggest concern going into the lesson--would their minds go in the direction that I wanted them to go in?
Since I was nervous, I had everything planned out exactly. For example, I was afraid that some student would open the seed as soon as he got his hands on it, so I directed them to place them on the paper towel for our physical observations. Because I was so prepared, the lesson went smoothly. However, as it was pointed out to me, I had too much control over the lesson. I realize that the whole point of this discovery method is so that children can be in charge of their own learning. I really like this theory of learning because I think it can work, but I realize that I may have more trouble implementing it than I first thought. As a result of my control, I did not allow any colloquium to occur during the lesson. I did not even realize that I was forfeiting this important step. I know it will be hard for me to sit back more and let the students do more of the work, finding out information on their own. In my later lessons I will definitely be aware of this and allow my students to discuss their findings amongst themselves. I totally dominated the lesson with my speech. It is strange to have someone comment on how much I talk during a lesson, since I am usually so quiet. However, I did not realize that I said so much. That is something that I will also have to be more aware of, and avoid, in future lessons.
One thing that I thought I did really well was to build the students' interest. We had placed the lima beans in the water yesterday and I made them promise not to look at them. When I arrived this morning, they immediately began asking me if they could go look at the beans. By the time I started my lesson, they were on pins and needles, anxious to find out what had happened to the beans. The surprise was evident. They verbally expressed their findings when they looked at the seeds. It was such a good feeling to have students who were so ready to learn about what had happened. At this point, I should have let them talk amongst themselves about the changes in the seed. They would have had no trouble listing three or four observations about the wet seeds. Instead, we did it as a group. When it came time to look in the seed, I think I led them to that point nicely. I had planned to have them draw what they saw, but when I assigned them to the task, all I got were blank faces. So, not giving my students any credit, or even a chance to find anything to draw, I show them the drawing that I have made of the inside of a seed. I am going to have to trust my students more, and at least give them a chance to make some discoveries. I did not want them to get frustrated, but I did not wait long enough, I know.
The final part of the lesson was the most fun, but also the scariest. I wanted them to act out, as a class, what happens to the food inside a seed as it grows under the ground. Because I was nervous about the way they would behave, I had too much control over this activity as well. I should have told them the situation, sat back, and let them show me what they understood. I found out very quickly that they did not understand that the food made the embryo grow. As time passed, they tried to make some of the food leave the seed. They understood that the food supply was dwindling, but they were unclear as to where it was going. I stepped in at this point and cleared up the confusion. They were then able to act it out correctly. Maybe I should have called them back to their seats, gone over what happens to the food, and then let them act it out. Either way, they really enjoyed the drama activity. I was really surprised at how well they behaved. I was also surprised about how much it told me about how much they understood about my lesson.
After the lesson, I had several requests for extra lima bean seeds. They wanted to take the experiment home and show their parents. That tells me that they really enjoyed the lesson. They were very excited about "showing off" their knowledge to their parents. Also, I had several more questions come up. For example, one child asked me how bit the embryos grow during the two weeks or so that they are underground. I had some bean sprouts that I had purchased from the grocery store to show him, but I was not sure how "old" the sprouts were. His question would have led into another great discovery lesson. In my own classroom, we would have sprouted some beans to answer his question. I was pleased that he asked the question. It proved to me that children can really be curious enough to want to learn, I just have to foster that curiosity.