Leaf Photosynthesis NetLogo Model

The Concord Consortium
Type Category
Instructional Materials
Interactive Simulation
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.


This Java-based NetLogo model allows students to investigate the chemical and energy inputs and outputs of photosynthesis through an interactive simulation. The simulation is a visual, conceptual model of photosynthesis and does not generate quantitative data. The central concept in the model is the role of chlorophyll in capturing light energy, and this concept is presented without delving into the biochemical details of the photosynthetic reactions. This allows students to focus on the core idea that photosynthesis transforms light energy into chemical energy. Along with exploring the basic process of photosynthesis, students can investigate the effects of light intensity, the day-night cycle (assuming the most common C3 photosynthetic pathway), CO2 concentration, and water availability on the rate of sugar production during photosynthesis. The model highlights the cycling within the chloroplasts between excited and unexcited states as energy is captured and released by chlorophyll. The lesson is written as an introductory learning experience, beginning with the question: What is needed for photosynthesis in a leaf, and what is produced? This resource is best suited as one in a series of learning experiences that either reinforce or extend the concepts addressed here. The model is embedded within an electronic form that provides instructions and guiding questions. Teachers and students should note that the electronic form does not save user data. An important limitation is that the model relies heavily on students’ visual perception, and this may pose a barrier for some students.

Intended Audience

- none -
Educational Level
  • High School
  • Middle School
Access Restrictions

Free access with user action - The right to view and/or download material without financial barriers but users are required to register or experience some other low-barrier to use.

Performance Expectations

HS-LS1-5 Use a model to illustrate how photosynthesis transforms light energy into stored chemical energy.

Clarification Statement: Emphasis is on illustrating inputs and outputs of matter and the transfer and transformation of energy in photosynthesis by plants and other photosynthesizing organisms. Examples of models could include diagrams, chemical equations, and conceptual models

Assessment Boundary: Assessment does not include specific biochemical steps.

This resource was not designed to build towards this performance expectation, but can be used to build towards it using the suggestions provided below.

Comments about Including the Performance Expectation
While this resource was developed well before the NGSS, it aligns very well with the selected Performance Expectation and the corresponding clarification statement and assessment boundary. The lesson centers on a conceptual computer model of photosynthesis, in which students see the chemical inputs and outputs of photosynthesis entering and leaving a leaf. Importantly, the model also highlights the role of the chloroplasts, and the chlorophyll within, in capturing energy from sunlight and storing that energy in chemical bonds. In contrast to many other online simulations, this model presents this core concept without moving into the biochemical specifics of the light reactions and carbon fixation.

Science and Engineering Practices

This resource was not designed to build towards this science and engineering practice, but can be used to build towards it using the suggestions provided below.

Comments about Including the Science and Engineering Practice
This lesson directly engages students in using a computer model of photosynthesis. The science and engineering practices represent both knowledge and skills to be mastered by students. To be successful in this lesson, students must learn to manipulate the model and the included parameters and to make sense of the information communicated by the model. The lesson text provides a great deal of scaffolding to help students make sense of the model, but teachers should be prepared to provide additional support. In particular, slowing down the model can reduce potential confusion while viewing the model. Students may benefit from other activities that allow them to directly generate or interact with evidence of matter and energy flows occurring during photosynthesis. The model provides students with qualitative, but not quantitative, evidence of the inputs, outputs, and rate of photosynthesis. Students may benefit from additional learning activities that provide an opportunity to collect and analyze such data. Teachers should also note that this lesson leaves two important gaps in addressing the practice cited above. First, the lesson does not call for students to develop or revise a model. Teachers might address this aspect of the practice by asking students to develop and revise their own model after studying the computer model. Student models could include diagrams, chemical equations, or conceptual models. If students engage in hands-on investigations, then evidence from those investigations could be used to develop and support the student models. Second, the lesson does not call for students to predict relationships between components of the photosynthetic system. This aspect of the practice could be addressed through a combination of hands-on investigation and student model development. For example, students might use their models to predict the outcomes of student-designed experiments that explore how different variables (e.g., light intensity, light color, or CO2 concentration) affect photosynthesis in plants. A final important consideration is the need to engage students in examining the strengths and limitations of any model they use in science. Here are some points to consider with this lesson. The strengths of the model lie in the representation of the overall flows of matter and energy into and out of the process of photosynthesis and in the fact that the model highlights the role of the chloroplasts in converting light energy to chemical energy. As is the case with all models, there are several important limitations. (1) The model shows a single leaf, rather than a whole plant. Teachers can help students think about how the concepts here translate to the full plant, including the metabolic needs and processes of the plant and the different processes occurring in the leaves, stems, and roots. (2) The model provides a macroscopic view of photosynthesis without delving into the cellular and biochemical processes. This can be seen as a strength and limitation. In classes in which students are ready to move beyond this conceptual view, teachers will need to design or select additional learning experiences. (3)The model is certainly based on evidence, but the model does not provide students with direct access to that evidence.

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
Rather than simply explain the concepts of the Disciplinary Core Idea to students, the simulations and guiding questions built into the lesson are designed to guide students toward developing the understanding that energy from sunlight is being stored in the bonds of sugar molecules. With this student-centered approach, teachers must be prepared to monitor and support student understanding through individual, small-group, and whole-class questioning and discussions. Based on this monitoring, teachers may need to provide additional learning experiences to ensure that all students have developed the appropriate understanding.

Crosscutting Concepts

This resource appears to be designed to build towards this crosscutting concept, though the resource developer has not explicitly stated so.

Comments about Including the Crosscutting Concept
The model, lesson text, and guiding questions emphasize the inputs and outputs of matter and energy during the process of photosynthesis. Transfers of matter will likely be more obvious to students than energy transfers. Therefore, teachers will need to pay particular attention to supporting students in understanding how light energy is stored in the chemical bonds of sugar. The model presents a single leaf as the photosynthetic system. Teachers might wish to engage students in a discussion of matter and energy transfers at other system levels, ranging from the chloroplast, to the cell, to the entire plant. One way to support students in recognizing explicitly the flows of matter and energy on various scales within the plant would be to facilitate a class discussion focused on a diagram of the plant at one level and an individual cell at another level. Through questioning students, the teacher could guide the class through tracking the inputs and outputs of matter and energy and discussing how these relate to the process of photosynthesis. Alternatively, this type of explicitly tracking inputs and outputs could be incorporated into an extension activity in which students develop and revise their own models based on hands-on investigations.

Resource Quality

  • Alignment to the Dimensions of the NGSS: Alignment to the Dimensions of the NGSS Comments: While no single learning activity can fully address a three-dimensional Performance Expectation, this model can be incorporated into an instructional sequence—which might include live investigations, data analysis, reading, writing, class discussion, and embedded assessments—that would support student mastery of this Performance Expectations. Teacher-facilitated discussion of the model can highlight the strengths and limitations of this particular model, as well as the crosscutting concept of matter and energy.

  • Instructional Supports: This simulation does engage students directly in using a model of a core life science concept, but it is a narrowly focused learning experience. Teachers will need to combine this resource with other learning experiences to fully support student learning. The guiding questions do prompt student sense making and conceptual understanding. However, the lesson as designed does not provide for teacher or peer feedback. Teachers are encouraged to modify the lesson to incorporate these features. To accomplish this, it is important to remember that the online form does not save student entries. Teacher notes are not provided.

  • Monitoring Student Progress: The model and guiding questions are aligned to the Performance Expectation and do elicit evidence of students’ performance relative to the Performance Expectation. However, rubrics are not provided and no structure is provided for teacher feedback. Teachers will need to modify or enhance the lesson to accomplish this. An important limitation to student accessibility is the reliance of the model on the interpretation of visual information. Students with vision or visual processing limitations will likely require a different learning activity.

  • Quality of Technological Interactivity: The interactive model is aligned to the Performance Expectations and does respond to student input, allowing students to investigate the effects of various factors on the rate of photosynthesis. The supporting text and guiding questions also provide effective support for students in using and understanding the model. While it would be better if the visual display of the model was more elegant, and if the model generated quantitative data, even in its current form, it meets the needs of students.