Friday, October 19, 2012

Stem Hypotheses/Stem Dissection

What do you think will be inside 
of the sunflower’s stem?

S:  Green stuff.
T:  Saliva.
O: I think flowers are in the stem.
L:  Wood stuff. Like basically green wood.
F:  Sap like in a tree but it’s green.
B:  I think that there’s some little sunflower seeds inside.
K:  I agree with S. Like when you take the top off a green acorn. Like the same sticky green stuff.
I:  I know exactly what’s inside the stem because I open a lot of stems. It’s clear but wet. It’s not sticky, it’s like juice, like a stem kind of juice. It’s not yummy.
D: Green watery goo. It’s not sticky.
R: I actually think it’s a bunch of water.
O: I agree with D.
L:  I agree with Isabel.
K:  I agree with Dillon.
E: I think there’s gonna be like green blood inside.
N: It might be a little hollow in the middle and some green juice stuff will be there.
L: There is a green watery goo in there.
Theories about what’s inside the stem:  HOLLOW or SOLID

The children broke up into small groups to to draw what they thought that they would see once we cut open the stem. They were asked:  what is your hypothesis? They were invited to share their drawings with their group and think further about the two ideas about the stem that have been offered up:  is the stem hollow or solid...or something completely different?  After their discussion, each group was given parts of a dissected stem to investigate further and cut up more as they liked. They drew what they saw and then discussed as a group their observations and how their ideas had changed. 

L: This (indicates his drawing) is the green gooey stuff. That’s inside. You cut the head off and it squirts out….are we actually going to split these in half (indicates stem)? 
D: I drew a line of seeds waiting to get blown away by the wind. The duplication mechanism is in effect.

     Are you drawing the inside of the stem?
     D: The Duplication Mechanism is inside as well. That’s why it’s invisible.
     O: I think there are more layers of the stem. Except thinner. The first one you take off is thick. Then the next one you take off is thinner. It gets thinner and thinner until you get to the middle.
     Like an onion?
     O: Yeah, except thinner.
     F: When I snap a flower off there’s this green like sap.
     That’s what you think is inside the stem?
     F: Uh-huh…These (indicates drawing) are the strings of sap. They’re like strings but they’re really sticky. 

    What do you think it will feel like inside?
    K: Soft. Dry.
    D: I think it’s gonna feel like seeds because seeds are inside.
    O: It’s gonna be wet like liquid.
    O: I think it’s gonna be clear goo. Not sticky.
    O: Like water…There aren’t seeds inside of it but there is a seed on the sunflower. That one seed goes up and it becomes more and more seeds.
    But how does it grow more seeds from just one?
    O: There’s seeds inside of the seeds.
    K: What does duplication mean?
    D: A second of the exact same thing.
    And how does that relate to the sunflower seeds?
   O: Cause you’re duplicating the seeds. 
    D., L. and O. explain that they are wondering about how the seed being planted could duplicate itself to create the many many seeds in the sunflower head.

    The children each begin to dissect a section of the sunflower stem.
    L: It is juicy.
    F: See, it is green sap.
    L: It’s not sap, it’s water.
    F: Dip it on your piece of paper, you can write.
   O: Pull the skin off. There are these veins, and gooey stuff.
    F: (examining a flower bud on her section of stem): Open your little buds up, you can see the petals….It’s a seed!
    L: Look(indicates part of stem), it’s celery.
   O: It has this white thing in the middle….[It’s] the core probably. It helps to stand up.
   O: Look, it looks like Oliver’s kind of right. It is a layer.

    I. works to get the right color): [This is what color] I think is in there. A little dab of green (makes a dot) then spreads. I know what’s in there, it’s not a guess. Clearish, yellowish, greenish stuff that feels a lot like spit. It’s the opposite of sap. Because it’s not sticky clear. Sap feels like glue.
   K: I agree with Isabel and I drew the whole inside of the stem, the spine and the gooey stuff.
   T: Kinda wet but also green. I kind of disagree with Isabel because I peel all kinds of plants—dandelions…
   N: These were extra details—a lot of details. But what I really want is the darker green outside, in the inside is greenish, yellowish, whiteish, clearish with a little bit of blue.
   They cut their sections of stem.
   T:  Nolan was right, there was a little bit of blue. 

T. shows a knife dissecting the stem as well as a close-up view
E: "I think I will see green wet goo (I mean water) inside. It's like sap.  These are veins in the leaf. I see green wet stuff, the blood of the stem."
"I saw a white line inside. I think it's a tiny core."
Close up view of the inside of the stem
F's detailed look at the stem

     B. noticed something interesting once we dissected the plant.  She noticed that if you squeezed the stem, "the juice comes up."  She also tried "painting" her picture of the leaf with the juice and saw that it was greenish - "Look!  The water inside the core is dirty!"  While we haven't had any discussions about chlorophyll, B. was the first student to observe the color of the liquid inside the plant.  

     After the class shared its findings, it was noted that there was indeed a core inside the plant.  They looked through books about plants and thought more deeply about the concept of a core.  E. compared it to a human spine - what we ourselves need for support and strength:

Marty later brought in a dried up sunflower and then peeled back the exterior to reveal the "core" within.  Looking at the white interior core generated a lot of excitement.  They noticed that the core felt soft, smooth, and wet to the touch.

T: I think the white core grows when the flower grows.  It's the tube that brings the water.
K:  I think when it rains, the core gets wet. 

What other living things have cores?
S:  Carrots have cores inside.
E:  The core keeps flowers from flopping over.   
L:  A tree has a core.
O:  Our body has a core.
T:  It's our bones. 

1 comment:

  1. What great ways to get the kids excited about earth science.