Photosynthesis, Part 4 - It's all "write"!

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As a culminating task, students will write about the process of photosynthesis, showing the vital connection between the sun and the energy needs of living systems.

Big Idea

Writing in science is about more than lab reports.


5 minutes

What organelle helps plants capture sunlight?

Given the two previous lessons (Photosynthesis, Part 1 and Photosynthesis,Part 2), this question should be readily answered by most, if not all students in the classroom.  Listen for the accuracy of the multiple voice responses, even when students are responding chorally as a group.   

Assess individual student understanding by asking individual students if they agree or disagree with the choral response and then ask them why they agree or disagree.  Asking students to explain “why” helps to assess the depth of content comprehension. Also, extending student responses beyond the choral response to random selection of students for the "why" response creates an environment and expectation that you are a teacher who calls on all students, whether they volunteer or not.



Review Activity

10 minutes

Create and copy sets of photosynthesis chemical reaction cards on 8 ½ x 11 colored paper.  I like to use cardstock paper because its more durable than copy paper.  I also suggest laminating the copy pages to help keep them sturdy for use over time. After copying and laminating enough pages for your class, cut the page into the individual cards on the page. Place the sets of cards in envelopes or sandwich bags for a review activity that is played as a game in groups of two in the following steps:

  • Issue a set of cards to each group of two students.
  • Make sure that no one opens the bag until you give the signal to start.
  • Explain that the intent is to use the cards to represent the chemical reaction of photosynthesis.
  • Count, “1-2-3, Go!” and release student to work.
  • Instruct groups to call you over to check their work once they think they have correctly modeled photosynthesis using the cards in the bag.

Walk around the room and observe as students work with the cards. Look and listen for student behavior and comments that signal understanding.  Offer assistance as needed in the form of guided questions that lead students to make the correct associations to complete the task.  For example, “Are reactants on the right or left side of a forward reaction?” Or, “Why do you think the card, photosynthesis is included?  Is it a label or one of the reactants or products?”

Note that the card sets includes the words cell respiration, mitochondria and chloroplast/ chlorophyll.  Look for groups to place the chloroplast/ chlorophyll card with the photosynthesis related cards to demonstrate they know that photosynthesis occurs in the chloroplasts of plant cells.  However, expect the cell respiration and mitochondria cards to cause confusion for most groups.  These two cards are included so that students will consider why and how they relate to the process of photosynthesis after completing the photosynthesis modeling activity.

As groups complete the task, check for accuracy and give them pieces of candy when they are done, reminding them to place all candy paper in the trash.  Assign groups that complete the task correctly without assistance to turn and assist groups around them that are still working.  The goal is for every group to be able to correctly model the chemical reaction for photosynthesis. 

After a check of every groups' work, ask a student to summarize the reaction for the entire class. Affirm the accuracy of the response and ask other students to elaborate, if needed.  Close the review by asking if anyone can explain why the cell respiration and mitochondria cards are included. Tell students that the cards are related to the process of cell respiration.  Challenge groups to show you the process of cell respiration.  Take a quick look around the room to see if any group can model respiration.   If no one is able to explain the association, use the cards with magnets on the white board to demonstrate how cell respiration is the reverse reaction of photosynthesis.  Have the groups model the reverse reaction by simply changing the direction of the arrow card and replacing the label, photosynthesis with the label, cell respiration.

Guided Practice

5 minutes

The culminating assignment for photosynthesis consists of writing a story about the process photosynthesis.  Explain that students will write a story about photosynthesis using a picture that you provide and vocabulary terms associated with photosynthesis.  To address different learning styles, display the instructions using a LCD projector while verbally explaining the task.   I typically provide verbal and written explicit instructions because some students more easily understand verbal instructions and others, written instructions.

After explaining what the task involves, display the picture using an LCD or digital projector. Make sure that students identify each of the numbered parts of the picture and emphasize the directions of the arrows in the picture.  Refrain from making any connections for students as the intent, at this point, is for them to be able to make the connections for themselves. 

Display the vocabulary terms. Read each of the vocabulary terms aloud and have students say each term after you.  Vocabulary acquisition includes both sight recognition and the ability to correctly pronounce terms, which makes this actions a good way to reinforce both.  Show students an example of correct usage of a term and a non-example of incorrect or unclear usage of a term so that they will know what to do and not to do when using the vocabulary terms in their stories:

Non-example: Photosynthesis is good.

Example: The tree uses sunlight energy to convert carbon dioxide and water into glucose and oxygen. 

Present the rubric for the writing task.  Point out that the rubric indicates that students with a mastery level knowledge of photosynthesis should be able to use 15-17 of the terms correctly in context of the stories they create.

Conduct a quick check for understanding by asking 1-2 students to restate the assignment in their own words.  This practice is a great way to ensure that everyone understands what they are being asked to do.

Close the guided practice by reviewing the 5 elements of story writing using a catchy rap found on the Flocabulary website.  

Independent Practice

20 minutes

The writing process can be highly effective in strengthening students’ concept comprehension.  But, often students will struggle with an assignment like this which requires them to take a concrete subject and apply it to a less concrete task.  Expect the frustration that some will have and be available to assist them as they work through the process of writing a story about photosynthesis.  Identify which students will work independently to complete the task.  For those students who might be challenged by the assignment, create sentence starters or assign students to with differing strengths to work together on the story development.   For those with the greatest struggles, spend a little time with them and have them talk about the picture first.  Ask them to tell you what they know from the picture before asking them to move into expressive writing.  The student work that is attached reflects the various ways that students approached the task and still were able to demonstrate understanding of the concept.


5 minutes

Engage students in a whole group discussion about what they found difficult about the assignment and what they enjoyed about the assignment.  Listen for aspects of the assignment that students found difficult and consider ways to modify or scaffold those aspects for future lessons.  Listen for those aspects that students enjoyed and consider working those aspects into future lessons.  This type of student feedback helps to ensure that students' needs are being met as instruction is planned and executed.