Detecting Photosynthesis

Contributor
Jennifer Kaelin
Type Category
Instructional Materials
Types
Lesson/Lesson Plan , Image/Image Set , Activity
Note
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be “fully aligned,” the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.

Reviews

Description

This data analysis activity includes all supporting materials including color photos of leaf sets that can be analyzed by students.  The leaf sets show the results (including controls) of what happens to ivy leaves under a variety of conditions, such as the absence of sunlight and in a plastic bag to limit CO2 intake,  as well as the results from starch tests done on the leaves exposed to each condition.  This lesson plan is a good foundation to a lesson sequence surrounding the requirements of photosynthesis.  From the observations that students make of the data and the resulting analysis, students will be able to develop conceptual understanding of how light and air are required for photosynthesis and develop some potential ideas to test regarding the other needs of plants to complete photosynthesis.

Intended Audience

Educator and learner
Educational Level
  • Grade 8
  • Grade 7
  • Grade 6
  • Middle School
Language
English
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

MS-LS1-6 Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms.

Clarification Statement: Emphasis is on tracing movement of matter and flow of energy.

Assessment Boundary: Assessment does not include the biochemical mechanisms of photosynthesis.

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
Students can analyze the appearance of the leaf sets to develop their understanding that light energy and air (CO2) are needed for the process of photosynthesis to occur. The photos of leaf sets show the results of whether the leaf contained starch or not. Since starch is a polymer of sugar molecules, students will need this information available to them. The teacher must allow students time to develop their own analysis of the pictures. Students will need to have the background information (provided in the materials) on the starch test in order to understand what the spots indicate. Students should have some background understanding that starches are chains of sugar (glucose) molecules and that the glucose molecules are matter that has energy stored in its chemical bonds. The teacher should build a lesson sequence around this activity since the students will need to understand the matter inputs/outputs of the photosynthesis reaction.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
This is a great opportunity to analyze another scientist’s data to develop potential explanations. Students should be given the opportunity to review several sets of photos to verify that the results are consistent. The teacher should allow small groups to make observations of the sets and record their ideas. Students can discuss their interpretation of the data in small groups and then report out to the class. The teacher can facilitate the discussion to be sure that all data is discussed, but students should be the ones framing the ideas.

Disciplinary Core Ideas

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
The teacher will have to allow students time to analyze the results of the testing and develop some ideas about why starch is not as prevalent in the leaves that were covered with foil and the leaves that were in a bag. The teacher should use probing questions to elicit student ideas during class discussion in order to allow sharing of collective ideas. Through development of the ideas from this activity, students can build their understanding through a lesson sequence that addresses the phenomena of photosynthesis. This disciplinary core idea is implicit within this activity as it is written, but can be made explicit through careful class discussion and further lessons that illustrate the process.

Crosscutting Concepts

This resource is explicitly designed to build towards this crosscutting concept.

Comments about Including the Crosscutting Concept
As student groups add their own interpretation of the results, each group can discuss why this is happening and develop a model of the phenomena of photosynthesis. In the model, energy can be represented by one type of arrow and matter can be represented by a different arrow. This will allow students to demonstrate their understanding of how the cycling of matter is driven by the flow of energy through plants during the process of photosynthesis. The first draft of the model may not be complete/accurate but can be revised as students discuss their ideas with the class and review the ideas of other groups. The teacher should explicitly look for how the relationship between the cycling of matter and the flow of energy is understood by students and ask probing questions if it is not explicitly shown in the model. (note that modeling is not the NGSS practice that is included as the lesson is written, but modeling will make the crosscutting concept of Energy and Matter more explicit.) The observation of leaves that were covered from sunlight having no/less starch should be a clincher to illustrate how the flow of energy is absolutely necessary for the process to occur.

Resource Quality

  • Alignment to the Dimensions of the NGSS: This lesson allows students to view the results of an investigation that was well-designed with multiple variables as well as a control. Through photographs, the investigation shows the outcome of leaves being deprived of sunlight for several days, as well as other leaves being deprived of air (CO2) for several days. The resulting starch is also shown in photos of the leaves after being tested for the presence of starch. The results are simply shown in photos, allowing the students to develop their own analysis. The phenomenon of photosynthesis is a strong example of the cycling of matter and the flow of energy and gives some explicit data to show these processes. The lesson should be part of a progression that builds student understanding through several steps.

  • Instructional Supports: The variables chosen to test and photo sets provide an exemplary set of data for students to analyze. The accompanying lesson plan and suggested questions are lacking true support for guiding a discussion among middle level students. The teacher will need to facilitate groups that are not developing ideas by asking some probing questions that get them on track with analysis.

  • Monitoring Student Progress: Although some questions are provided to the teacher to check for understanding, it would be better for the teacher to check in with each group multiple times to determine the level of their understanding. The addition of developing a model to show the process of photosynthesis will also allow the teacher to determine what students understand and what they are lacking.

  • Quality of Technological Interactivity: The photo set is high quality and can be printed or shared via classroom portal for use in 1:1 classrooms. Additionally, the links to videos are current and show relevant ideas that can be provided to students for additional information.