--- title: "Where is all the carbon?" subtitle: "Year 9 Earth and space · The carbon cycle · Lesson 2" --- # Where is all the carbon? **Name:** {{field-24}} **Date:** {{field-15}} **Class:** {{field-15}} > **Key question:** The carbon atoms in your body have been in dinosaurs, in ocean water and in the air, many times over. They are billions of years old and still in use. :::teacher-note **In one sentence:** Students identify carbon stores in each of Earth's spheres, distinguish stores from flows, and explain that carbon moves between stores without being made or destroyed (AC9S9U03, node 2). **Students should be able to say:** I can name a carbon store in each of Earth's four spheres. I can explain the difference between a carbon store and a carbon flow. I can explain that carbon moves between stores but is never made or destroyed. **Width:** the unmarked parts are the floor every student does (Engage, Explore, Explain, Evaluate). Typical and Wider sections add contexts, not difficulty. Students work in the online tutorial alongside this sheet. ::: ## Engage :::keep-together **Which of these holds the most carbon?** ☐ All living things on land ☐ The air ☐ Coal, oil and gas ☐ The oceans My prediction, and why: {{lines-3}} ::: :::teacher-note **What happens:** The oceans, by far: about 38 000 billion tonnes, roughly 50 times what is in the air. (Rocks such as limestone hold even more, but that carbon moves very slowly.) ::: ## Explore Try it on the board in the tutorial. Was your prediction right? What was different? {{lines-2}} ## Explain: stores in every sphere :::keep-together ### Which sphere **Which sphere is each carbon store in?** Groups: Atmosphere, Hydrosphere, Biosphere, Geosphere - Carbon dioxide in the air: {{field-15}} - Carbon dioxide dissolved in sea water: {{field-15}} - Carbon in trees and animals: {{field-15}} - Dead leaves and roots in soil: {{field-15}} - Coal, oil and natural gas: {{field-15}} - Limestone (calcium carbonate) rock: {{field-15}} ::: :::teacher-note **Answer:** Carbon dioxide in the air → Atmosphere; Carbon dioxide dissolved in sea water → Hydrosphere; Carbon in trees and animals → Biosphere; Dead leaves and roots in soil → Biosphere; Coal, oil and natural gas → Geosphere; Limestone (calcium carbonate) rock → Geosphere ::: :::keep-together ### Store or flow **What is the difference between a carbon store and a carbon flow?** ☐ They mean the same thing ☐ A store is where carbon is kept; a flow is carbon moving from one store to another each year ☐ Stores are in the air; flows are in the ocean ::: :::teacher-note **Answer:** A store is where carbon is kept; a flow is carbon moving from one store to another each year Stores are measured in tonnes of carbon; flows in tonnes a year. Photosynthesis is a flow from air to living things. ::: :::keep-together ### A burning log **When a log burns, what happens to its carbon?** ☐ It turns into energy ☐ It is destroyed by the fire ☐ It moves into the air as carbon dioxide: the same atoms, in a different store ::: :::teacher-note **Answer:** It moves into the air as carbon dioxide: the same atoms, in a different store Carbon is never made or destroyed. Burning moves it from the biosphere to the atmosphere. ::: :::keep-together ### Steady **The air's carbon stayed steady on the board, even though more than a hundred billion tonnes moved in and out each year. Why?** ☐ Nothing was really moving ☐ The board stops the air changing ☐ The flows into the air and out of it were balanced ::: :::teacher-note **Answer:** The flows into the air and out of it were balanced A store stays the same when what flows in equals what flows out, like a bath with the tap on and the plug out. ::: :::keep-together ### Fast or slow **Fast or slow? How long does carbon usually stay in each store?** Groups: Fast: years to centuries, Slow: millions of years - Carbon dioxide in the air: {{field-15}} - Carbon in a gum tree: {{field-15}} - Dead leaves in the soil: {{field-15}} - A coal seam: {{field-15}} - Limestone rock: {{field-15}} ::: :::teacher-note **Answer:** Carbon dioxide in the air → Fast: years to centuries; Carbon in a gum tree → Fast: years to centuries; Dead leaves in the soil → Fast: years to centuries; A coal seam → Slow: millions of years; Limestone rock → Slow: millions of years ::: :::typical ## Elaborate: carbon in the landscape :::keep-together ### Carbon everywhere **Which of these things in a landscape store carbon?** ☐ Only the air ☐ Only the trees ☐ Trees, soil, the sea, the air and limestone cliffs: every sphere ::: :::teacher-note **Answer:** Trees, soil, the sea, the air and limestone cliffs: every sphere Carbon is everywhere: it is part of every living thing, dissolved in water, in the air, and locked in rocks. ::: ::: :::wider ## Elaborate: shells to stone :::keep-together ### Shells to stone **Sea creatures take carbon dissolved in water to build shells of calcium carbonate. When they die, the shells pile up and, over millions of years, become limestone. Which stores has that carbon moved through?** ☐ Hydrosphere → biosphere → geosphere ☐ Atmosphere → atmosphere ☐ Geosphere → biosphere → hydrosphere ::: :::teacher-note **Answer:** Hydrosphere → biosphere → geosphere Rocks such as limestone are the largest carbon store of all, but their carbon moves out very slowly, mostly over millions of years. ::: ::: ## Evaluate: look back Write one sentence: "At first I thought… Now I think… because…" **Revision summary** - Carbon is stored in every sphere: **atmosphere** (carbon dioxide), **hydrosphere** (dissolved in the oceans), **biosphere** (living things, dead matter, soil) and **geosphere** (fossil fuels, limestone and other rocks). - The oceans hold far more than the air; rocks hold the most of all. - Carbon is never made or destroyed. It **flows** between stores: the **carbon cycle** is the map of those flows. - A store stays steady when the flows into it balance the flows out. ## Exit ticket :::keep-together **Name a carbon store in the hydrosphere and one in the geosphere, and one flow that moves carbon into the atmosphere.** {{lines-3}} ::: :::teacher-note **Answer:** Hydrosphere: carbon dioxide dissolved in the oceans. Geosphere: fossil fuels or limestone. Flow into the air: respiration, decay, burning or release from the oceans. :::