This unit builds toward the following NGSS Performance Expectations (PEs): 

• 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.
• MS-LS2-3: Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem.
• MS-PS1-3: Gather and make sense of information to describe that synthetic materials come from natural resources and impact society. 

Partial NGSS Performance Expectations (PEs) addressed by this unit:

• MS-LS1-2: Develop and use a model to describe the function of a cell as a whole and ways the parts of cells contribute to the function. (Specifically, chloroplasts and mitochondria.)

The unit expands students’ understanding of matter cycling and photosynthesis, which include these Grade 6-8 DCI elements:

LS1.C: Organization for Matter and Energy Flow in Organisms

• Plants, algae (including phytoplankton), and many microorganisms use the energy from light to make sugars (food) from carbon dioxide from the atmosphere and water through the process of photosynthesis, which also releases oxygen. These sugars can be used immediately or stored for growth or later use.

LS2.B: Cycle of Matter and Energy Transfer in Ecosystems

• Food webs are models that demonstrate how matter and energy is transferred between producers, consumers, and decomposers as the three groups interact within an ecosystem. 
• Transfers of matter into and out of the physical environment occur at every level. Decomposers recycle nutrients from dead plant or animal matter back to the soil in terrestrial environments or to the water in aquatic environments. 
• The atoms that make up the organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem.

PS1.A:  Structure and Properties of Matter

• Each pure substance has characteristic physical and chemical properties (for any bulk quantity under given conditions) that can be used to identify it.

PS1.B: Chemical Reactions

• Substances react chemically in characteristic ways. In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants.

PS3.D: Energy in Chemical Processes and Everyday Life

• The chemical reaction by which plants produce complex food molecules (sugars) requires an energy input (i.e., from sunlight) to occur. In this reaction, carbon dioxide and water combine to form carbon-based organic molecules and release oxygen. (secondary)

The placement of this OpenSciEd Unit 7.4 and associated units are shown in the OpenSciEd Middle School Scope and Sequence.

• Developing and Using Models
• Constructing Explanations and Design Solutions
• Engaging in Argument from Evidence
• Obtaining, Evaluating, and Communication Information

• Systems and System Models
• Energy and Matter

Which elements of the Nature of Science are developed in the unit?

• Science knowledge is based upon logical connections between evidence and explanations. (NOS-SEP)
• Science assumes that objects and events in natural systems occur in consistent patterns that are understandable through measurement and observation. (NOS-CCC)

How are they developed?

• Students begin developing models to explain and later build explanations about where the food for plants is coming from; they revise those explanations as they gather evidence from their investigations.
• Students build their science knowledge about chemical reactions based on logical and conceptual connections they make using evidence from their investigations about where plants, animals, and decomposers get their food and how they use it over the course of the unit.

In this unit, students’ investigations are motivated by an anchoring phenomenon of trying to figure out where their breakfast foods (such as the maple syrup and sap they can taste during Lesson 1) come from. Maple sap is a puzzling context in which to explore the cycling of matter and flow of energy among living and nonliving parts of an ecosystem and the role of photosynthesis in those processes.

Each OpenScied unit’s anchoring phenomenon is chosen from a group of possible phenomena after analyzing student interest survey results and consulting with external advisory panels. We chose maple syrup/sap (and other breakfast foods) as the anchoring phenomenon for this unit because students are likely familiar with maple syrup, but when they pause to think about the fact that it comes from trees, they have all kinds of questions: Why do trees have this? Where does it come from? Where is it going? The time of year when it is flowing to be tapped is when the tree appears dormant–what’s going on there? Students might connect to other plants making sweet fruits to attract pollinators, but that doesn’t seem to be the case with the sap, so what is it doing for the tree? When students consider other breakfast foods they’ve eaten (an opportunity to localize this anchor and include various cultures), they realize that plants contain not just sugars, but also fats and proteins, and they wonder how plants are getting all these food molecules. Why do plants need food? Where does a plant’s food come from? All of these questions motivate students to figure out how matter cycles and energy flows among living and nonliving parts of an ecosystem, focused especially on plants and photosynthesis.

This unit is designed to be taught after students have experienced the Healing Unit and the Inside Our Bodies Unit. As such, work in this unit can leverage ideas about cell structure and function as well as understanding about how our bodies break down food molecules into smaller pieces that can be used for different functions. Additionally, this unit uses and builds on the system models and modeling practice that students have developed in earlier units. Prior to this unit, students will have developed system models within a life science phenomenon in the Healing Unit and the Inside Our Bodies Unit. In addition, students will have built system models in the Cup Design Unit when determining what components of a cup system affect the temperature of the liquid inside, and the Storms Unit when figuring out what causes storms. In this unit, students will develop a system model that involves the interactions of both living and nonliving components.

This unit is designed to be taught prior to the Palm Oil Unit where students figure out that the decline of orangutan populations in Indonesia that is linked to the use of palm oil in food and household products we use everyday, so that students can go to leverage ideas about food webs, producers, consumers, and interactions between these organisms in an ecosystem.

In this unit, students develop and use a model to explain the cycling of matter and flow of energy in a system comprised of living and nonliving components. This model includes mechanisms for both photosynthesis and cellular respiration. Their model traces the paths of carbon, hydrogen, and oxygen atoms through the ecosystem as living things produce and/or use them as food. The model tracks the flow of energy into the ecosystem through sunlight and its conversion to energy that can be used by living things. Students’ models build on their ideas from OpenSciEd Unit 7.3: How do things inside our bodies work together to make us feel the way we do? (Inside Our Bodies Unit). In that unit, they figured out that food contains particular types of molecules (sugars, fats, proteins), and that chemical reactions in animal’s bodies  break down these molecules and form new molecules that support growth and/or release energy, and can be stored for later use. This unit takes up the additional question of how and why plants have these molecules that animals  can use and focuses on how these molecules move between the living and nonliving parts of the ecosystem.

This is the fourth unit in 7th grade in the OpenSciEd Scope and Sequence. Given this placement, several modifications would need to be made if teaching this unit earlier in the middle school curriculum. These include:

• If taught before OpenSciEd Unit 7.1 or at the start of the school year, supplemental teaching of classroom norms, setting up the Driving Question Board, and asking open-ended and testable questions would need to be added. (These supports are built into 7.1.)
• This unit is designed to come after two units involved in the foundations of chemical reactions and explicitly builds on those understandings. It is critical to note that students need the idea of chemical reactions and the idea that matter can be rearranged through these reactions yielding resultant materials with different properties to develop the explanations in this unit. Without these ideas, the questions raised make no sense to students, and they don’t have what they need to develop the disciplinary core ideas. If not being done in the standard OpenSciEd sequence, teachers would need to make sure there are other ways students have developed these foundational ideas, reflected in the PEs MS-PS1-1: Develop models to describe the atomic composition of simple molecules and extended structures and MS-PS1-2: Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. Students will also need an understanding that all matter is made of particles, which is foundational ideas for these PEs. MS-PS1-5: Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved.
• The unit is also designed to come after the extension of chemical reactions to living things that occurs in OpenSciEd Unit 7.3. If students have not done that unit before taking this unit on, there will need to develop the idea that there are chemical reactions in living things, reflected in the PE MS-LS1-7: Develop a model to describe how food is rearranged through chemical reactions forming new molecules that support growth and/or release energy as this matter moves through an organism. 
• Supplemental teaching of PEs MS-LS1-1: Conduct an investigation to provide evidence that living things are made of cells; either one cell or many different numbers and types of cells and MS-LS1-2: Develop and use a model to describe the function of a cell as a whole and ways the parts of cells contribute to the function. This unit does not introduce cells to students. It uses that prerequisite knowledge to build understanding that living things are made of cells and those cells have structures for specific jobs. This unit will add to that knowledge by looking at the role of chloroplasts and mitochondria. 

In Lesson 6, to represent the process of photosynthesis in a plant, 7th grade students use a NetLogo simulation to discover the relationship of how the inputs within the plant interact and affect the amounts of outputs and represent the process of photosynthesis in a plant. 

Prerequisite math concepts that may be helpful include:

• CCSS.MATH.CONTENT.6.NS.C.8: Solve real-world and mathematical problems by graphing points in all four quadrants of the coordinate plane.
• CCSS.MATH.CONTENT.6.SP.B.5.B Describing the nature of the attribute under investigation, including how it was measured and its units of measurement.
• CCSS.MATH.CONTENT.6.SP.B.5.C: Giving quantitative measures of center (median and/or mean) and variability (interquartile range and/or mean absolute deviation), as well as describing any overall pattern and any striking deviations from the overall pattern with reference to the context in which the data were gathered. 

In addition, within the domain of Measurement and Data in the Common Core Mathematics Standards, students will be drawing on what they have learned across a number of standards under the category of Represent and Interpret data for grades 1-5 when they are generating and interpreting the tables and graphs of their data collected from the simulation and during analysis of several input/output graphs in many lessons across the unit.

The following are example options to shorten or condense parts of the unit without eliminating important sensemaking for students:

• Lesson 11: Construct the explanation of how a maple tree lives through the seasons either as a class or as a home learning assignment.
• Lesson 12: If you are not tasked with addressing MS-PS1-3, in this unit, consider skipping synthetic materials activities which are parts 3-6 (about a day) in the Teacher Guide.
• Lesson 14 and 15: Choose only one assessment (either the assessment from Lesson 14 or from Lesson 15) to use at the end of Lesson Set 2.

To extend or enhance the unit, consider the following:

• Lesson 2: Instead of jigsawing the different food indicators, student groups could test each of the indicators with the corresponding type of food.
• Lesson 11: Provide time for students to work on the alternate activity described in the Teacher Guide where students dissect one of the seeds to look for evidence of that sprouting starting. You can also give students the option to each take three seeds from the investigation home, put them back in a wet paper towel in a ziplock bag as they were when students got them, and tape the bag to a window in their house to watch them sprout.
• Lesson 13: Students can carry out the What Happens to Uneaten Food? investigation in the classroom using BTB (like in Lessons 7 and 11) or the carbon dioxide/relative humidity detector (like they used in Lessons 4 and 10).
• Lesson 13: Students could spend more time researching details of their chosen decomposer and/or students could communicate the information they’ve learned in a different format than the suggested slide or to a different audience than just their peers.
• All lessons: Remove scaffolds provided with Science and Engineering Practices as a way to give students more independent work with the elements of these practices.

• Jamie Noll, Unit Lead, Northwestern University
• Tara McGill, Field Test Unit Lead and Reviewer, Northwestern University
• Dawn Novak, Writer, BSCS Science Learning
• Meghan McCleary, Writer, University of Illinois Extension
• Sue Gasper, Writer, University of Illinois Extension
• Katy Fattaleh, Writer, The Nora Project
• Michael Novak, Writer, Northwestern University
• Kate Cook-Whitt, Writer, Maine Mathematics and Science Alliance
• Emily Harris, Writer, BSCS Science Learning
• Tyler Scaletta, Writer, Chicago Public Schools
• Katie Van Horne, Assessment Specialist
• Kelsey Edwards, Project Coordinator, Northwestern University
• Christina Murzynski,  Project Coordinator, Northwestern University
• Misty Richmond, Pilot Teacher, James Ward School 
• Mary Colannino, Teacher Advisor, Hugh B. Bain Middle School
• Elizabeth Xeng de los Santos, Advisory Team, University of Nevada – Reno
• Chris Griesemer, Advisory Team, University of California – Davis
• Cindy Passmore, Unit Advisory Chair, University of California – Davis

BSCS Science Learning

• Christine Osborne, Copyeditor, Independent Contractor
• Valerie Maltese, Marketing Specialist & Project Coordinator
• Alyssa Markle, Project Coordinator
• Chris Moraine, Multimedia Graphic Designer

EdReports awarded OpenSciEd an all-green rating for our Middle School Science Curriculum in February 2023.  The materials received a green rating on all three qualifying gateways: Designed for the Next Generation Science Standards (NGSS), Coherence and Scope, and Usability. To learn more and read the report, visit the EdReports site.

An integral component of OpenSciEd’s development process is external validation of alignment to the Next Generation Science Standards by NextGenScience’s Science Peer Review Panel using the EQuIP Rubric for Science. We are proud that this photosynthesis unit for 7th grade students has earned the highest score available and has been awarded the NGSS Design Badge. You can find additional information about the EQuIP rubric and the peer review process at the nextgenscience.org website.