7.3 Metabolic Reactions – Unit Overview

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

• MS-LS1-3: Use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells.
• MS-LS1-5: Construct a scientific explanation based on evidence for how environmental and genetic factors influence the growth of organisms.
• 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.
• MS-PS1-1: Develop models to describe the atomic composition of simple molecules and extended structures.*

• 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.*

*This unit reinforces these NGSS PEs that students should have previously developed. In the OpenSciEd Scope and Sequence, these are first built in Unit 7.1. In this new context of metabolic reactions, students will engage in the analysis and interpretation of various forms of data on how molecules change or do not change as they move through digestion. Chemical reactions starting in our mouths and stomachs and continuing throughout the rest of the digestive system drive this change, breaking down large food molecules into smaller ones. Some molecules, like fiber, stay the same throughout digestion and, therefore, do not undergo chemical reactions.

The current version of the unit expands students’ understanding of metabolic reactions, which include these Grade 6-8 DCI elements: 

LS1.A Structure and Function

• In multicellular organisms, the body is a system of multiple interacting subsystems. These subsystems are groups of cells that work together to form tissues and organs that are specialized for particular body functions.

LS1.B Growth and Development of Organisms

• The growth of an animal is controlled by genetic factors,* food intake, and interactions with other organisms, and each species has a typical adult size range.

LS1.C Organization for Matter and Energy Flow in Organisms 

• Within individual organisms, food moves through a series of chemical reactions in which it is broken down and rearranged to form new molecules, to support growth, or to release energy. 

PS3.D Energy in Processes and Everyday Life

• Cellular respiration in plants and* animals involves chemical reactions with oxygen that release stored energy. In these processes, complex molecules containing carbon react with oxygen to produce carbon dioxide and other materials.   

*There is a slash through the pieces of the DCIs that are not developed in this unit. In the OpenSciEd Scope and Sequence, students will develop an understanding of genetic factors in the OpenSciEd Unit 8.5, how plants do chemical reactions to obtain and store energy in the subsequent OpenSciEd Unit 7.4, and interactions with other organisms in the ecosystem dynamics in OpenSciEd Unit 7.5.

In addition, this unit introduces the concept of food as fuel and lays the groundwork for future units in which students figure out that both food and other sources of fuels are sources of matter and sources of energy, drawing connections between chemical reactions that transfer and convert energy in living and nonliving systems. This connects to the idea identified on page 196 of Framework for K–12 Science Education (National Research Council, 2012): “By middle school, a more precise idea of energy—for example, the understanding that food or fuel undergoes a chemical reaction with oxygen that releases stored energy—can emerge.” 

You can view the placement of this OpenSciEd Unit 7.3 and associated units within the OpenSciEd Middle School Scope and Sequence. 

• Developing & Using Models
• Analyzing & Interpreting Data
• Engaging in Argument from Evidence

• Systems & System Models
• Structure & Function

In Lesson 8 students use a NetLogo simulation to discover the relationship between the rate of food absorption and the height of villi that line the small intestine. 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.RP.A.2: Understand the concept of a unit rate a/b associated with a ratio a:b with b ≠ 0, and use rate language in the context of a ratio relationship. 
• CCSS.MATH.CONTENT.7.SP.C.6: Approximate the probability of a chance event by collecting data on the chance process that produces it and observing its long-run relative frequency, and predict the approximate relative frequency given the probability. 
• CCSS.MATH.CONTENT.7.SP.C.8.C: Design and use a simulation to generate frequencies for compound events.

Students analyze and interpret M’Kenna’s height and weight growth charts in Lesson 10. Prerequisite math concepts that may be helpful include:

• 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 food molecule graphs in many lessons across the unit.

This is the third 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:

• Introducing the students to the concept of a Driving Question Board and a shared set of classroom norms. This would not be necessary if taught after other OpenSciEd units.
• Supplemental teaching of the nature of matter, so that students see matter as made of particles.
• Supplemental teaching of the foundations for chemical reactions in 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. This unit is designed to come directly 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.

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 the organization of the body goes from cells, to tissues, to organs, to subsystems to multiple subsystems working together in one body system.

• Tara McGill, Unit Lead, Northwestern University
• Michael Novak, Field Test Unit Lead, Northwestern University
• Kate Cook-Whitt, Writer, Maine Mathematics and Science Alliance
• Kathryn Fattalah, Writer, The Nora Project
• Emily Harris, Writer, BSCS Science Learning
• Lindsey Mohan, Writer, BSCS Science Learning
• Jamie Noll, Writer, Northwestern University
• Barbara Taylor, Writer, Charles A. Dana Center at University of Texas Austin
• Heather Galbreath, Pilot Teacher, Lombard Middle School
• Michael Clinchot, Teacher Advisor, John D. O’Bryant School of Mathematics and Science
• Nicole Vick, Reviewer, Abingdon-Avon High School
• Betty Stennett, Reviewer, BSCS Science Learning
• Katie Van Horne, Assessment Specialist
• Kelsey Edwards, Project Coordinator, Northwestern University
• Barbara Hug, Unit Advisory Chair, University of Illinois at Urbana-Champaign

BSCS Science Learning

• Natalie Giarratano, Copyeditor, Independent Contractor
• Stacey Luce, Editorial Production Lead
• Valerie Maltese, Marketing Specialist & Project Coordinator
• Alyssa Markle, Project Coordinator
• Chris Moraine, Multimedia Graphic Designer

An integral component of OpenSciEd’s development process is external validation of alignment to the Next Generation Science Standards by Achieve’s Science Peer Review Panel using the EQuIP Rubric for Science. We are proud that this unit has been identified as a quality example of a science unit. You can find additional information about the EQuIP rubric and the peer review process at the nextgenscience.org website.