Shedding Light On Photosynthesis

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SWBAT describe the discoveries that promoted our understanding of photosynthesis, recite the equation, and discuss the importance of the chemical reactions that occur to allow photosynthesis to occur.

Big Idea

Why are plants important? What's the big idea with trees? Students will breath in knowledge of photosynthesis and the vital role the process plays in our daily life.

Lesson Introduction: Turn On The Lights!

1 minutes

The video clip discusses this the introductory nature of this lesson as the students venture into their study of photosynthesis and cellular energy.  All of the vocabulary in this lesson is new, so be patient as your students as they discover this content for the very first time.    

Hook - Lighting Up With Energy

5 minutes

In a prior lesson, students learned about plant cells and the function of the chloroplast, but this lesson dives into the chemical reactions of photosynthesis inside of the chloroplast.  Most students have never been introduced to the fine details that explain the chemical reactions that occur to allow the process of photosynthesis to occur.  Since this lesson is just an introduction/review that familiarizes your students with the process of photosynthesis the majority of the details will be covered in later lessons.

Have the students number their paper #1-4 and respond to the following prompts:

The possible types of energy that will be discussed in this activity are solar/light energy, mechanical energy, and chemical energy.

  1. A solar-powered calculator uses solar cells that are placed at the top of the device.  The calculator uses solar/light energy and converts it to what type of energy to allow you to solve your math problems?  
  2. Plants use light energy from the sun to make their food (autotrophic).  What kind of energy is the light energy converted into to provide food for the plant?
  3. Most plants have some green structures.  What causes plants to appear green?  You can discuss the pigment in the plant or why we see the color green.
  4. What does the green color have to do with the plant's ability to convert light energy into the energy in the food it makes?  

The students will share their answers with their neighbor.  The teacher will provide a more detailed explanation of topics that students identify as difficult or troubling.   A class discussion will provide more information on how the chlorophyll absorbs the sun's light to initiate the chemical reaction of photosynthesis.  

Students will feel comfortable talking about plants due to their prior experiences with plants at home or in nature, but the concept of energy conversion will be new.  No need to get hung up in the details of the chemical reaction at this point.  This activity is designed to get students thinking of how plants convert light energy into chemical energy!

Direct Instruction - The Brightest Minds

25 minutes

In an effort to provide all students the necessary prior knowledge to be successful in studying photosynthesis, this lesson will introduce students to the scientists who helped pave the way for our understanding of how plants grow, the process of photosynthesis, and the detailed chemical reaction that occurs between plants, animals, and our environment.  Students will title their papers, "Shedding Light On Photosynthesis".  These Lecture Notes will continue to be an introduction to the process of photosynthesis by scaffolding the structure of the necessary vocabulary terms and scientific contributions to build a strong understanding of this process. 

The teacher will read the equation for photosynthesis out loud in front of the class.  Students are then encouraged to mimic the teacher's words during the second reading in an effort to reinforce student learning.

Photosynthesis Equation translated to words:

"Six molecules of carbon dioxide combined with six molecules of water in the presence of sunlight and chlorophyll will yield one molecule of glucose and six molecules of oxygen."

Student Recitation of the Photosynthesis Equation:

Independent Practice - Powered By The Sun

15 minutes

Students will use their introductory lecture notes to develop an illustrated model that conceptualizes the cycling of matter during the chemical reactions of photosynthesis.  This lesson is just the introduction to photosynthesis so students are encouraged to keep their models very basic and focus soley on the inputs and outputs of the chemical reaction.

 Sample of Student Work #1: Photosynthesis Model - This artifact demonstrates the student's attention to detail while trying to master the intricate chemical processes associated with photosynthesis.  The student's effort will support her learning as she examines the diagram to follow each phase of the process as sunlight is converted to stored chemical energy.

Sample of Student Work #2: Photosynthesis Model - This artifact displays a student's work that appears to be rushed with very little effort.  The greatest concern is that the illustrated model is difficult to read so the student would have a tough time going back to study the model while trying to prepare for an assessment.  Students do not have to be talented artists to be successful in this assignment, but they do need to have attention to detail and attempt to make their illustrated model as neat as possible in order to support their learning of the content.

These models will be used in the next lesson as students work to develop a detailed narration that depicts the intricate chemical reactions of photosynthesis.


Close - Back To The Dark Ages

10 minutes

As a final review of today's introductory lesson, your students will have the opportunity to participate in a creative writing project that crosses over to their study of history as well!  

It is a time for you and your students to take a trip back in time nearly 300 years ago (not quite the Dark Ages, but still way back in history!).  Once you have exited your time machine, you have found yourself in the mid-eighteenth century farm on the English countryside.  You decide to stay and help out as a farmhand where you observe and help the daily routines of the farmer.  After you have stayed for a few months, you notice the growth pattern of the your farmer's crops.  Using your most advanced knowledge from 300 years ago (keeping in mind the lack of technology and lack of available search engines), attempt to respond these prompts:

  1. Why does the farmer need to water the crops each day?
  2. What causes the plants to grow?
  3. Why are the plants all green?
  4. Why do some of the plants seem to grow faster than others?


Now consider the same prompts using the knowledge of photosynthesis that we now enjoy today as a result of the great scientists who came before us:

  1. Why does the farmer need to water the crops each day?
  2. What causes the plants to grow?
  3. Why are the plants all green?
  4. Why do some of the plants seem to grow faster than others?


What would it have been like living 300 years ago and trying to figure out the "why" and the "how" of the scientific workings of our planet?  We do not want to take for granted the work and discoveries of our forefathers who paved the way for our current understanding of science and the universe.

 Students will complete their creative writing responses as homework and share as an opening activity in the next lesson.

Samples of Student Creative Writing: Student were challenged to go back in time and try to figure out how farmers learned about growing plants.  Then they time-warped to the present day and attempted to answer the same questions using our understanding of photosynthesis.  Students enjoyed the comparison of the creative writing pieces and the freedom to use their imagination!