]Lesson 5 - Explaining How Animals Grow

Download PDF of Lesson 5 Teacher's Guide

Students learn and use a scientific model to explain digestion and biosynthesis using the Three Questions.

Guiding Question

How do animals use food to grow?

Activities in this Lesson

Activity 5.1: Tracing the Processes of Cows Growing: Digestion and Biosynthesis (40 min)
Activity 5.2: Molecular Models for Cows Growing: Digestion and Biosynthesis (40 min)

Note: The molecular modeling part of Activity 5.2 is exactly the same as the molecular modeling for biosynthesis in the Plants and Decomposers units. Additionally, it is a 2-turtle activity which means it involves a higher level of complexity. Consider skipping the activity if you have already taught it in another unit or if it is too advanced for your class.

Activity 5.3: Explaining How Cows Grow: Digestion (40 min)
Activity 5.4: Explaining How Cows Grow: Biosynthesis (40 min)

Unit Map

Unit Map Lesson 5

Target Performances

Lesson 5 – Explaining How Animals Grow (students as explainers)
Activity 5.1: Tracing the Processes of Cows Growing: Digestion and Biosynthesis	Students “zoom in” to the structure and function of a cow’s organ systems and cells, tracing atoms and energy.
Optional Activity 5.2: Molecular Models for Cows Growing: Digestion and Biosynthesis	Students use molecular models to explain how polymers are broken into monomers during the process of digestion and monomers are linked into polymers during biosynthesis.
Activity 5.3: Explaining How Cows Grow: Digestion	Students explain how matter moves and changes and how energy changes during digestion in a cow (connecting macroscopic observations with atomic-molecular models and using the principles of conservation of matter and energy).
Activity 5.4: Explaining How Cows Grow: Biosynthesis	Students explain how matter moves and changes and how energy changes during biosynthesis in a cow’s cells (connecting macroscopic observations with atomic-molecular models and using the principles of conservation of matter and energy).

NGSS Performance Expectations

Middle school

MS. Matter and its Interactions. MS-PS1-1. Develop models to describe the atomic composition of simple molecules and extended structures.

High school

HS. From Molecules to Organisms: Structures and Processes. HS-LS1-2. Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.
HS. From Molecules to Organisms: Structures and Processes. HS-LS1-6. Construct and revise an explanation based on evidence for how carbon, hydrogen, and oxygen from sugar molecules may combine with other elements to form amino acids and/or other large carbon-based molecules.

Three-dimensional Learning Progression

The three activities in this lesson complete the Explanations Phase of the Animals unit. This involves modeling and coaching with the goal of helping students develop atomic-molecular scale accounts of the digestion, and biosynthesis that were drivers of the macroscopic changes they observed in their Mealworms Eating investigation in Lesson 3.

Key Ideas and Practices for Each Activity

Activity 5.1 is the first part of the Explanations Phase of the instructional model (going down the triangle) for digestion and biosynthesis. Students trace the chemical changes of digestion and biosynthesis in the body of a cow using a poster of a cow.

Activity 5.2 is a 2-turtle activity appropriate for advanced middle school or high school students and classes. If you decide not to teach 5.2, you can move directly from 5.1 to 5.3. In 5.2, students model the chemical changes of digestion and biosynthesis using paper molecules. This activity introduces and uses the vocabulary of polymer and monomer, as well as the names of specific monomers.

Activity 5.3 is the second part of the Explanations Phase of the instructional model (going down the triangle) for digestion. Students use the Explanations Tool to construct final explanations of what happens when animals break large organic molecules from their food into small organic molecules. This activity is appropriate for students who did only 5.1 and students who did both 5.1 and 5.2, but the vocabulary used to describe the molecules will be different depending on what activities were taught. Ideally, at this phase their explanations will combine evidence from macroscopic-scale observations during the investigation with their new knowledge of chemical change at the atomic-molecular scale.

Activity 5.4 continues the second part of the Explanations Phase of the instructional model (going down the triangle) for biosynthesis. Students use the Explanations Tool to construct final explanations of what happens when animals use small organic molecules to gain mass. This activity is appropriate for students who did only 5.1 and students who did both 5.1 and 5.2, but the vocabulary used to describe the molecules will be different depending on what activities were taught. Ideally, at this phase their explanations will combine evidence from macroscopic-scale observations during the investigation with their new knowledge of chemical change at the atomic-molecular scale.

Key Carbon-Transforming Processes: Digestion and Biosynthesis

Content Boundaries and Extensions

Talk and Writing

This lesson of the unit represents the fading portion of the Explanations Phase. This means that students are expected to develop explanations for carbon-transforming processes they studied in this unit in new and novel contexts. The table below shows specific talk and writing goals for the Explanations phase of the unit.

Talk and Writing Goals for the Explanations Phase	Teacher Talk Strategies That Support This Goal	Curriculum Components That Support This Goal
Examine student ideas and correct them when there are problems. It’s ok to give the answers away during this phase! Help students practice using precise language to describe matter and energy.	Let’s think about what you just said: air molecules. What are air molecules? Are you talking about matter or energy? Remember: atoms can’t be created. So that matter must have come from somewhere. Where did it come from? Let’s look at the molecule poster again… is carbon an atom or a molecule?	Molecule Poster Three Questions Poster
Focus on making sure that explanations include multiple scales.	The investigation gave us evidence for what was happening to matter and energy at a macroscopic sale. But what is happening at an atomic-molecular scale? What is happening to molecules and atoms? How does energy interact with atoms and molecules during chemical change? Why doesn’t the macroscopic investigation tell us the whole story? Let’s revisit our scale poster… what is happening to matter at the molecular scale?	Molecular Models Molecular Modeling Worksheets Explanations Tool PPT Animation of chemical change Powers of Ten Poster
Encourage students to recall the investigation.	When did this chemical change happen during our investigation? How do we know that? What is our evidence? What were the macroscopic indicators that this chemical change took place?	Evidence-Based Arguments Tool Investigation Video
Elicit a range of student explanations. Press for details. Encourage students to examine, compare, and contrast their explanations with others’.	Who can add to that explanation? What do you mean by _____? Say more. I think you said _____. Is that right? Who has a different explanation? How are those explanations similar/different? Who can rephrase ________’s explanation?	Explanations Tool