Engage in the class discussion, then answer question 4.
(20 min) Instruct students to look back at their Student Activity Sheets from Lesson 16 , focusing on the pictures of molecules found in trees.
Have students look for N, P or K in these diagrams.
Suggested Prompt:
Do you notice N, P or K in any of these molecules? Which of the nutrients are present in carbohydrates, fats and proteins? Which of these nutrients are not present in carbohydrates, fats and proteins?
Listen for student responses , such as:
We see that all proteins contain N. None of these contain P or K. Suggested Prompt:
Last class we learned about mitosis and how that process is responsible for growth. When a cell goes through mitosis, does it copy anything else besides carbohydrates for the cell wall?
Listen for student responses , such as:
We know that all living cells contain DNA so DNA must also be copied when cells divide. Have a whole group discussions about the role of DNA in our bodies.
Suggested Prompt:
Think back to genetics, DNA is the build block for what molecule? When we have a strand of DNA what should it eventually form?
Listen for student responses , such as:
We know that in animals, DNA make amino acids that builds proteins DNA is the building block for amino acids, but is it the same for plants? Have a whole group discussion about the role of DNA in plants.
Suggested Prompt:
Think back to to genetics, what did we figure out about DNA? Where have we figured out stuff about DNA before? What do we know DNA does?
Listen for student responses , such as:
We know that DNA is suppose to make an exact copy of itself in order to reproduce, but something things go wrong We figured out that both humans and bacteria contain DNA
Once students remember that both humans and bacteria contain DNA, continue the discussion about DNA in plants based on what they know about living things and how they reproduce. Now that students figured out that DNA works the same in plants as it does in other living thing, they need to continue to look at why the plants need N, P, and K.
Now, direct students to the Molecular Formula Diagrams of DNA in their Student Activity Sheets , instructing them to look for N, P and K.
Suggested Prompt:
Do you notice N, P or K in DNA? Which of the nutrients are present? What are we still missing? How can we figure this out?
Listen for student responses , such as:
We see that DNA contains N and P but not K. We are still wondering what plants use the K for. We decide we could google it. Either on the teacher’s computer or on a student’s phone, do a Google search for what plants use potassium for and discuss the results as a class.�
Suggested Prompt:
What does the internet say plants use potassium for?
Listen for student responses , such as:
Plants use potassium to make roots, fruits and flowers. Suggested Prompt:
Someone asked earlier, ‘What happens to the plant if the soil doesn’t have the right nutrients?’ Now that we know what they are for, what do we think? How do you think we can fix soil that doesn’t have the proper nutrients?
Listen for student responses , such as:
I think the plants will not grow right if they don’t have the right nutrients. If the plants lack potassium they probably will not grow fruit If the soil doesn't have the right stuff, I think you can put fertilizer in it to help it. Optional - Have a bag of fertilizer or a picture of one, as you show students the bag ask them what they notice. They should notice that the fertilizer has the same nutrients that we tested for in the soil.
Direct students to summarize the discussion on their Making Sense item #4 section of the Student Activity Sheet .