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Plants | Lesson 2 - Foundations: Zooming into Plants

Lesson 2 Foundations: Zooming into Plants

Students “zoom into” plants, animals, and decomposers to learn about structures and functions that they all share:

  • All organisms are made of cells.
  • All the functions of organisms are done by their cells.
  • All cells are made of molecules, including large organic molecules (fats, carbohydrates, and proteins).
  • All functions of cells involve moving and changing molecules.

Guiding Question

What makes up our food?

Activities in this Lesson

Note: Activities 2.1, 2.2, and 2.3 are
repeating activities:
They are the same in the three organism-scale units: Animals, Plants, and Decomposers. Activity 2.4 focuses specifically on plants. Teach Activities 2.1, 2.2 and 2.3 during the first of the organism-scale units you teach (Animals, Plants or Decomposers). These activities can be skipped when you teach subsequent organism-scale units. Activity 2.4 is different for each unit though and should be taught each time.

  • Activity 2.1: Zooming into Plants, Animals, and Decomposers (40 min)
  • Activity 2.2: Molecules Cells Are Made of (45 min)
  • Activity 2.3: Molecules in Cells Quiz (20 min)
  • Activity 2.4: Questions about Plants (20 min)


  1. Describe systems and processes in a hierarchy of scales, including atomic-molecular, macroscopic, and large scale.
  2. Identify the most abundant organic materials in foods—fats, proteins, and carbohydrates—and use food labels to find out how concentrated they are in different foods and animal tissues.

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-LS1-6. 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.

Background Information

Lesson 2 focuses on essential foundational knowledge that students will need to achieve the objectives for this unit. In this lesson students learn to read nutrition labels to identify the key materials in the foods we eat, which are also the materials in plant and animal bodies. The activities in this lesson serve as the Foundational Knowledge and Practice Phase of the Instructional Model, where students are introduced to key ideas and practices that they will use throughout the rest of the Plants unit.

In Activity 2.1, students review the anatomy of a molecule using the Molecule 11 x 17 Poster to refresh their memory of the precise use of words we use to describe matter at the atomic-molecular scale. Then, students examine nutritional labels to learn that there are three broad classes of materials in food:

  • Organic materials, including fats, proteins and carbohydrates (sugars, starches, and indigestible fibers such as cellulose). These are the key materials that make up biomass (everything but water) of all living things and are essential for life.
  • Vitamins and minerals, including sodium, iron, calcium, and many others. These materials are also essential for life, but only in small amounts—less that 1% of almost all foods.
  • Water is not listed on nutrition labels, but it makes up more than 50% of the mass of almost all plant and animal bodies and almost all the foods we eat. Students can figure out how much of a food is water by subtracting the mass of the organic matter from the total serving size (100 grams for all the nutrition labels used in this lesson).

Activity 2.2 uses nutrition labels as the basis for a simplified account of the materials that foods—and the living organisms that foods come from—are made of. All living things are made of thousands of different substances, all created by the plants from glucose, water, and soil minerals. Carbon TIME units emphasize the most important of these macromolecules: polysaccharides (including starch and cellulose), fats or lipids, and proteins. Many other essential macromolecules such as nucleic acids are left for more advanced treatments.

The large organic molecules (sometimes called macromolecules) in plants, animals, and decomposers are actually much larger than the molecules shown in the presentation and modeling activity:

  • Fatty acids typically contain 10 to 25 carbon atoms.
  • Proteins can consist of hundreds of amino acids. Humans are typical of many organisms in that our proteins contain 21 different kinds of amino acids.
  • Starch and cellulose molecules can be made of hundreds or thousands of sugar monomers. Different kinds of starch and fiber can also include other 5-carbon and 6-carbon sugars besides glucose.

Activity 2.1 is the Predictions Phase of the instructional model (beginning the climb up the triangle). During this phase, students record their predictions and express ideas about what happens to plants when they are in the light and the dark as well as where a plant’s mass comes from as it grows. They use the Predictions Tool to do this.

Although we hope that students will come to appreciate the vast number and complexity of biomolecules, our emphasis in Carbon TIME is on helping students understand that all of this complexity arises from a simple starting point—glucose and minerals—and a few simple chemical processes in biosynthesis.

Although there are obvious differences in the chemical composition of plants, animals, and decomposers, the Carbon TIME units emphasize their similarities. Most of the monomers (sugars or monosaccharides, amino acids, fatty acids and glycerol) in all living things are created in plants and made into polymers by the plants. Animals and decomposers break these polymers back down into monomers through the process of digestion, then alter the monomers and build new polymers through their own biosynthesis.

In activity 2.3, students take a short quiz to check their knowledge of these concepts before applying these ideas throughout the rest of the Unit.

In activity 2.4, students begin to consider questions about cells related specifically to plants, which they will study throughout the unit.

Key Carbon-Transforming Processes: Photosynthesis

Lesson Map:

See the Plants Unit Read Me document for more details.

Unit Map for Lesson 2

Unit Map

Plants Lesson 2 Unit Map

Talk and Writing

At this stage in the unit, the students will be learning Predictions Phase, the Foundational Knowledge and Practice that is important for the rest of the unit. The table below shows specific talk and writing goals for this phase of the unit.

Talk and Writing Goals for the Foundations Phase

Teacher Talk Strategies That Support This Goal

Curriculum Components That Support This Goal

Treat this as background information.

We want to talk about a few basic practices and some basic knowledge to prepare us for the unit.


Listen for student ideas about matter and energy at different scales, and attend to wrong ideas.

What is happening to matter and energy at ______ scale? Who can explain?

Are you in the macroscopic scale or the atomic-molecular scale?

Who can explain that at a different scale?

The PPT that “Zooms into” the macroscopic subjects of the unit: a leaf, a potato, air, fossil fuels, etc.

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 at different scales.

Let’s think about what you just said: food molecules. What are food 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?

Let’s revisit our scale poster… what is happening to matter at a macroscopic scale?

Powers of Ten Poster

Molecule Poster

Three Questions Poster


Grade student ideas. 


There is a quiz during this phase of the unit to help you decide if your students are ready to move on.