Lesson 6 of 14
Objective: Students observe the external and internal parts of a plant and flower to understand how this plant survives and reproduces.
Dissecting a daffodil was the best way for students to explore the inside of a flower. Through this student driven dissection process, they can see how the external and some of the internal parts work to help the plant survive. (If you are not familiar with the daffodil and how to dissect it, consult this informative site for your benefit. But, I encourage you to completely allow them to problem solve on how to do the dissection of the plant.)
I began my lesson by opening up a page on my SB that showed labeled internal and external parts of the daffodil. I began by explaining that it isn't normally ok to just start pulling apart daffodils because the blooms are just once a year and we were doing it to learn about the structural parts of the plant. Then, I referred to the SB picture of the daffodil, telling them how to label parts of the daffodil as they drew what they saw from the dissection. I passed out a coloring sheet from the internet that had the proper parts labeled appropriately and served as a reference to proper vocabulary. I made one copy for each table team so they could have a reference, but also draw the daffodil in their notebooks as they dissected. I explained that they would drive their own experiment by collaborating with their team as to how they should dissect the plant and decide how to show their discoveries.
I told them they would need a daffodil, scissors, their notebook, colored pencils and their daffodil sheet. After they collected their materials, we headed to the lab where we could work with a little more space.
The Dissection Begins
As they found their places at tables, I told students they needed to talk about how they would dissect and explore the daffodil. I told them to discuss:
What will you start with?
How will you note it in your notebook?
How can you depend upon one another to be sure you are accurate about the observations?
They began as I roved the classroom. I stopped to help with their examining daffodils and coach them a little if they seemed stuck. Students began explaining to me how they were going about pulling apart the corona to find the internal reproductive structures. Students questioned about how they should notate their observations and what was expected. I noticed that they were struggling with having to design this process on their own. I needed to intercede on several occasions until they got comfortable with the process and the experience. Sometimes when they asked specific direction, I simply coached them to make the choice and look at the drawing to see if they could match the part to the drawing, then hypothesize how that part the flower or plant served the plant.
They sketched in their notebooks and labeled the parts very easily, but I reminded them to look at the spelling of the structure so that they were more accurate.
An added fun thing I did was to take the anther and put it under a microscope for them to view what pollen looks like magnified. They took turns looking and using the microscope properly. I also wanted them to experience what the bulb looks like after dissecting it.
Dissection of the Bulb
I had planted daffodil bulbs early in the spring to prepare for this lesson. I was hoping they would bloom in time and just by chance, the timing was perfect. So, the forced bulbs served as visual engagement that evoked a lot of curiosity over the past weeks. It was exciting to see the daffodil bloom within the classroom, but today, I would up heave a bulb or two as part of our dissection experience. Prior to extracting the bulb out, I asked them what they thought they would see inside. They expected they would see green or a sprout of some sort. Some thought it would just be solid. As I unearthed the bulb, students could see how the bulb's root system looked. I cut the bulb in half to reveal the inside as they used their cameras on their iPad to document their evidence. They were surprised to see there wasn't anything very exciting inside the bulb except layers like an onion. So we talked about how an onion is like a daffodil bulb and that many bulbs tend to have some sort of layered structure.
After we completed this task and students finished their note taking and drawing, we gathered together to share "Aha" moments and the things that amazed us.
Our "Aha!" Moments
I got everyone's attention to stop their work and told them it was time for them to share their "Aha!" moments. This is always a favorite time in science after an investigation. As students shared, there were observations and comparisons made to other familiar plants.I asked them what they were surprised at and what they didn't know? I asked them to start with the sentence, "My aha moment was" and share their thinking using evidence from their observations to prove understanding that daffodils have specialized structures. One student shared that seeds look like corn to her. This important sharing what they learned time together helps to solidify arguments proving understanding that flowers have to have these specialized structures to survive and reproduce.