Unit 03 · Digestion, Metabolism & Energy Balance
Digestion and metabolism are how the body turns food into usable energy. This unit follows food as it’s broken down, traces how the body extracts the energy stored in nutrients, and treats the calorie for what it actually is — a unit of energy the body needs, not something to fear. You’ll see energy balance, energy in versus energy out, framed strictly as science: a way to understand how the body uses fuel, never a diet or weight-loss prescription. Mastery means you can trace digestion, explain the calorie honestly, and reason about energy balance from evidence.
| Criterion | Developing | Proficient | Mastery |
|---|---|---|---|
| Tracing digestion | Cannot describe what happens to food after it’s eaten. | Names a digestive organ or two but cannot trace food through the system. | Traces food through the digestive system and explains where it is broken down into nutrients the body can absorb. |
| Metabolism & extracting energy | Thinks the body uses food without changing it. | Knows the body gets energy from food but cannot say how. | Explains metabolism as the process that breaks nutrients down and releases the energy stored in them for the body to use. |
| The calorie as a unit of energy | Calls calories “bad” or something to be avoided. | Knows a calorie measures energy but still treats it as harmful. | Explains the calorie as a unit of energy the body needs to function — neither good nor bad, simply a measure of the fuel food provides. |
| Energy balance as neutral science | Treats energy balance as a rule for losing weight. | Describes energy in versus energy out but frames it as a diet prescription. | Describes energy balance — energy in versus energy out — as a neutral scientific concept about how the body uses fuel, not as a diet or weight-loss prescription. |
| Anchor lab (calorie & energy-balance calculation) | Cannot set up a calorie or energy-balance calculation. | Sets up the calculation but slips on the units or the arithmetic. | Completes a calorie and energy-balance calculation correctly and explains what the numbers describe about energy, using them as evidence rather than a verdict. |
| Integration (cross-domain) | Makes no supported connection between the source and the science. | Uses the source but needs help connecting evidence, writing, or limitations to the science. | Independently connects History, Reading, and Writing using a cited source, appropriate evidence, a limitation, and a scientific explanation. |
Integration is reported separately and cannot lower the science grade or block a science demonstration pass. Science and practical criteria determine that pass. Use the integration guide's evidence checklist for the separately reported criterion.
“Food gets broken down through the digestive system, and metabolism releases the energy stored in it — measured in calories, which are just units of energy the body needs. Energy balance is energy in versus energy out; it’s a way to understand how the body uses fuel, not a rule about weight.”
“Calories are bad and you’re supposed to avoid them, right? Digestion is just the stomach doing something. I’m not sure what energy balance even means.”
You demonstrate this unit through a calorie and energy-balance calculation where you trace the energy in food and explain what the numbers mean aloud — not a multiple-choice test. A criterion counts as mastered only when you can both do the calculation and explain energy balance as neutral science, never as a diet prescription. Mastery is demonstrated, not awarded.
A 5-page clipboard packet — unit overview, key terms, the mastery rubric, anchor examples, and a score sheet you can print and grade against.