Leaves Make Food

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Objective

Students will be able to name the process by which plants make food by conducting an investigation.

Big Idea

Covering the leaves of a plant helps students understand the important role leaves play in the process of photosynthesis.

Introduction

10 minutes

Gather students on the rug using a preferred classroom management technique. I like to use my “Stop, look, listen.” The students stop what they are doing, look at me and listen for the direction. I usually preface the direction with, “When I say go…” This reminds the students to listen to the whole direction before moving to follow the directive.

In this case I would say, “When I say go I would like you to clear your space, push in your chair and go take a spot on your dot. Walking feet go.” By saying walking feet I am reminding the students to use walking feet in the classroom to ensure safe movement between areas.

When all of the students are seated on their dot in the rug area I

I have already loaded the short video clip onto the SMARTBoard for the students to see to cut down on wasting instructional time. The link will take you to the page of a science site. You will need to scroll down the page to find the song - about two thirds down the page. 

Photosynthesis song

 

 

I use this musical video clip to engage my students’ attention. The video clip is used to peak my students interest and begin them thinking about how plants get food to stay alive and continue to grow. 

Activity

45 minutes

When the video is over I open up a picture of a plant on the SMARTBoard.

“Team 203 you and I are very lucky in that we can easily get readymade food from lots of places. We can get it from the kitchen, from a restaurant, from the garden and buy it from a store. Plants are not so lucky. They have to make their own food every day.”

“Can someone tell me how they think plants make their own food?”

I select a few students to respond to the question.

“Those were all good responses and great ideas.”

“Plants actually make their own food through a process called Photosynthesis. Can you all say the word photosynthesis?”

“Great. A plant needs three ingredients to make its own food. Does anyone want to take a guess as to what those ingredients are? I will give you a clue the song told us.”

I select students who want to respond until we get all of the “ingredients” named. 

As the students tell me the “ingredients” I write them on the SMARTBoard.

Drawing the photosynthesis process with the students.

Once we have all the needs written on the SMARTBoard I tell the students, “We are very lucky to have plants because they take in carbon dioxide, which is something we do not need and too much of it is not good for us. The plants take that carbon dioxide use what they need to make glucose and then release oxygen, which is something we need to breathe and stay alive. So do you think it is a good idea to keep plants around?”

I allow the students to call out the answer, “Yes!”

“You are very right. Plants are very important because they provide oxygen for other living things to breathe. That is a big reason why I keep so many plants in the classroom; they help keep our classroom air filled with oxygen.”

“Photosynthesis occurs in the plants green leaves. Chlorophyll provides the leaves with that healthy green color which helps them photosynthesize. As scientists what do you think would happen if you took all the leaves off a plant?”

I allow the students to call out the answer, “It will die!”

“That’s right. That is the reason why I ask you not to pull the green leaves off the trees out on the playground or off the plants in the garden. Every time we remove a living leaf we take away one more food making device for the plant.”

“Now what do you think would happen to the green chlorophyll in the plant leaves if we blocked the light?”

I select a few students to respond to the question.

“Those were good predictions and we are going to test what happens to leaves if we block the light by covering a few leaves on our biggest classroom plant.”

I take down the plant off its hanger and ask, “Who thinks they can tell me how we could cover up a few leaves?”

I select a student to respond.

“I think that is a good suggestion Colin; we could put a paper bag over the leaves. I will fold up a paper bag and paper clip it over this one leaf here. Anyone else got another idea how we could block the light?”

Working with students on covering the leaves 1.

Working with students on covering the leaves 2.

I continue along this line of questioning until we exhaust the ideas or the ideas become unrealistic in which case we discuss the validity of the idea.

“At one of your stations you are going to record what we did to our plant today. In five days we will take the coverings off, record what we observe and discuss our observations.”

Plant with covered leaves.

 “Does anyone have any questions?”

 

Once I feel the group has a good grasp of the instructions I send the students over one table group at a time to maintain a safe and orderly classroom. It usually sounds like this;

“Table number one go have some recording fun.

Table number two, you know what to do.

Table number three, hope you were listening to me, and

Table number four, you shouldn’t be here anymore.”

 

Allow the students 15-18 minutes to work on this activity. I remind the students to keep an eye on the visual timer so they will use their time wisely.

Students working on recording our experiment.

 

In this activity the students are exploring what happens to a leaf when it is no longer exposed to sunlight and can no longer photosynthesize. At the work station the students are practicing the scientific skill of recording what they observe on day one. We will revisit the experiment in five days or so depending on the school week, to remove the leaf coverings and record what we observe.

Of course the leaves will be much paler than their healthy green counter parts and this when we discuss the importance of chlorophyll and its role in the process of photosynthesis.   

Extensions

At one of the other integrated work stations the students are making a pictorial representation of the photosynthesis process (engineering/art).

  1. Instruct the students to draw a plant or flower on the paper.
  2. Have the students draw a sun above the plant to symbolize the sun's energy; or they could glue a piece of yellow construction paper or tissue paper onto the paper.
  3. Tell the students to add a source of water for the plant. This can be in the form of raindrops or groundwater. Aluminum foil makes nice shiny water droplets.
  4. On the left side of the paper, have the students write the words "Carbon Dioxide" or have a resource label depending on your students’ abilities. Draw an arrow leading from the term to the plant to show that the plant is taking in the carbon dioxide from the environment. Some students may elect to draw a picture of a human or animal breathing out and that is acceptable.
  5. On the right side of the paper, have the students write the word "Oxygen" or have them use a resource label.  Draw an arrow pointing away from the plant to symbolize the release of oxygen into the surrounding air.
  6. Have your students draw a sugar cube or a pile of sugar, near the base of the plant to symbolize the glucose produced by photosynthesis. You could also provide some sugar and the students could glue it to the picture (be aware of ants in the classroom if you display this work).
  7. Explain to your students how each step of the process works while they are working on the representation.

Student working on representing the photosynthesis process 1.

Student working on representing the photosynthesis process 2.

Student sharing his photosynthesis work.

 

At another station the students are measuring leaves using non-standard forms of measurement – in this case cubes (math). 

Students measuring a variety of leaf images.

 

At another station the students are exploring how we use leaves to provide energy for us by taste testing a variety of edible leaves. They will try spinach, Romaine lettuce, Iceberg lettuce, cabbage, parsley and Arugula. I will lead this discussion towards food chains in preparation for our next unit which is the Forest unit; using words such as herbivore, omnivore and carnivore.

Leaf tasting station.

 

These activities provide the students with opportunities to explore leaves in different content areas. The activities allow students to expand their content skills while still maintaining a connection to the science lesson topic.     

Closure

10 minutes

When all four rotations of the integrated work stations are completed I blow two short blasts on my whistle and use the “Stop, look listen” technique mentioned above.

“When I say go, I would like you to clean up your space remembering to take care of our things, push in your chair, and use walking feet to go and take a spot on your dot. Walking feet – go.”

 

Once all of the students are seated on their spot I say, “Today your exit ticket is to tell me one thing needed for photosynthesis to occur. Remember your answer needs to be in the form of a complete sentence. For example, “One thing plants need for photosynthesis to occur is …””

Once a student has given me their response they are free to use the hand sanitizer and go to get their snack. If a student has difficulty in coming up with a response they do one of two things:

  1. Ask a  friend for help, or
  2. Wait until everyone has left the rug area and we will work on a response together.

 

I use this exit ticket process as a way for the students to explain what they observed from the lesson we just did. This quick assessment process allows me to see if the student is able to take information learned in one format and be able to relay that information verbally to another person.   

Assessment

In order to assess if my students have successfully understood and retained the information presented in the lesson I evaluate each student by providing them with a task the next day for morning work. For this assessment I place the following assignment sheet at each student’s seat.

The students’ are asked to fill in the blanks on the assessment page. Some students are able to read the directions themselves and others will require assistance. Knowing my students abilities helps me know which students will require assistance and which students can work independently.  

Link to the assessment page site - Education.com