Colorful Flowers Part 2-How Does the Stem Work?

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Students will be able to describe the function of the stem by completing an investigation.

Big Idea

How do they get those bright, pretty flowers? This lesson will show students how this happens and help them understand the function of the flower' stem.


10 minutes

This lesson is a continuation of Colorful Flowers-How Des the Stem Work-Part I.  Click here to navigate to that lesson.

Materials Needed: 

  • You will need the students predictions as recorded on Flower and Colored Water Experiment Recording Sheet included as a PDF with this lesson
  • The containers with the white flowers in colored water.  If your flower did not change substantially,  I encourage you to make a new cut (slitting up the stem) and adding more food color to the water.  Not all colors are taken in as well with the food coloring (that's okay if you have at least one container of flowers that did observe the colo

  I pass out the recording sheets to the students and I say to them, Today we are going to revisit our flower investigation.  Who can tell the class what this investigation is all about (I want the students to go through the steps and verbalize exactly what it is that we were doing with this experiment.  After we have reviewed what the investigation included, we moved to the big "reveal".

I wanted the reveal to be exciting, so I had the students close their eyes and put cover them with their hands while I put the vases out.  We are not set for the reveal.

The Big Reveal

10 minutes

We count  The students are excited as they open their eyes and see their flowers.  See video.  Some of them have collected a great deal of color.  Others have not as much.  There is one that is very surprising.  The flowers in the green food coloring did not turn green.  Instead these flowers are yellow. 

I say to the students, Now, I want you to make an observation about how the flowers changed and record it on your recording sheet.  Remember to use your crayons to show how the water and flowers look now.  Your sheet should show exactly how your investigation looks.

The students begin working and I circulate around the room to observe their work, reminding them to include details about their flowers.  See Work Sample.  I ask questions to probe students' thinking such as:

  • Was the entire flower red, or just the tips of the petals, etc?
  • Is the flower the same color as the liquid?
  • Is that what you expected to happened?
  • Why do you think only part of the flower changed color?
  • Why do you think some flowers are more colorful than others?


15 minutes

The students are still very excited about the results of the investigation.  I invite them to do a gallery walk so they look at the other flowers that were in different colors.  After everyone has had a chance to look at the flowers, we return to our seats and begin discussion.  I ask the students a few questions.

  • What happened to the flowers?
  • How do you think this happened?
  • Did the water change?  Why not?

(I made sure to touch on the water as many students predicted their would be a change to the water)

I then asked some questions that were specific to the results of our experiment.  You will need to adjust these questions based on the outcomes you had in your experiment.

  • Why do you think the flowers in the green water turned yellow instead of green? 
  • What two colors make up green? 
  • Why do you think only the yellow showed up and not blue? 
  • Did the flowers that were in the blue food coloring turned blue?
  • Why did we not get blue when we put the flowers in the green water?
  • Why do you think the red flowers only have a small amount of color?

Here is a video of some of our discussion.  As you can see, I am pushing the students to really think about the "why" of the results of this experiment.  I want them to be able to use their scientific knowledge as rationale for the experiments results.  At this age, I want them to start taking risks, and share their "whys".  I want them to know that it is okay to think outside of the box and to make connections in their learning.  Prompting and supporting my students in this way provided important scaffolding for future scientific thinking. 

The students bring up other items to discuss.  They wonder if a flower put in black would have black petals or if the different colors that make up black would show through in different spots on the flower.






10 minutes

Now it is time for us to have the students connect this lesson to stem of a plant and its function.  I say to the students, You thought that the water in the container went up the green part of the plant that we call the stem.  So the stem was sucking up the water and taking it up to the plant.  Can you think of something that you use that the stem is like (the students did not get this and needed further prompting).  When you go to a restaurant and get a glass of soda, what do you often use to drink it with (Yes, your mouth, but you always use that.  What do they give you to drink with?)  That's right, a straw.  How is the stem of our plant like a straw?  That's right.  It sucks up liquid and takes it to other parts of the plant.  Do you think that the stem takes anything besides liquid to the stem?

Tomorrow, we are going to learn more about the stem of a plant.  It does some very important things.  I want you to remember what we learned today about the stem and be ready to use this information during our lesson tomorrow.