Bushfire and ice
View Sequence overviewStudents will:
- determine the amount of carbon that is stored in the biomass of a local tree.
- calculate the amount of carbon removed from the atmosphere to produce the biomass.
Students will represent their understanding as they:
- calculate the biomass of a tree.
- use a spreadsheet to calculate the carbon present in the tree.
- use a spreadsheet to calculate the amount of carbon dioxide removed from the atmosphere during the growth of the tree.
In this lesson, assessment is formative.
Feedback might focus on:
- students’ ability to measure and calculate the biomass of a tree.
- students’ ability to use spreadsheets to calculate the amount of carbon dioxide that was removed from the atmosphere.
Potential summative task
Students working at the achievement standard should:
- analyse and connect data and information to identify and explain patterns, trends, relationships, and anomalies.
- analyse the impact of assumptions and sources of error in methods.
- construct logical arguments based on evidence.
- evaluate the validity of conclusions and claims.
- select and use content, language, and text features effectively to achieve their purpose when communicating their ideas, findings, and arguments to specific audiences.
Refer to the Australian Curriculum content links on the Our design decisions tab for further information.
Whole class
Bushfire and ice Resource PowerPoint
High Tech option: GPS receiver unit
Access to trees with a base circumference of at least 40cm
Each group
Tape measure
Each student
Access to spreadsheet software (i.e. Excel)
Measuring carbon storage Resource sheet
Lesson
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkRecall
Revise the carbon cycle diagram and graph from the previous lesson.
Discuss how carbon could be shifted into the slow cycle.
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkIdentifying and constructing questions is the creative driver of the inquiry process. It allows students to explore what they know and how they know it. During the Inquire phase of the LIA Framework, the Question routine allows for past activities to be reviewed and to set the scene for the investigation that students will undertake. The use of effective questioning techniques can influence students’ view and interpretation of upcoming content, open them to exploration and link to their current interests and science capital.
When designing a teaching sequence, it is important to spend some time considering the mindset of students at the start of each Inquire phase. What do you want students to be thinking about, what do they already know and what is the best way for them to approach the task? What might tap into their curiosity?
Read more about using the LIA FrameworkCarbon sinks
(Slide 35) Pose the question: How do trees take in and store carbon?
- Where do plants get their carbon from?
- Carbon dioxide in the atmosphere.
- What do plants do with the carbon?
- Through photosynthesis the carbon dioxide is combined with water to produce glucose sugar and oxygen molecules. This process transforms light energy into chemical energy.
- What carbon molecules are there in the plants?
- Genetic material (DNA), proteins, enzymes and sugars
Pose the question: How much carbon is stored in the plants in our school grounds?
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkThe Investigate routine provides students with an opportunity to explore the key ideas of science, to plan and conduct an investigation, and to gather and record data. The investigations are designed to systematically develop content knowledge and skills through increasingly complex processes of structured inquiry, guided inquiry and open inquiry approaches. Students are encouraged to process data to identify trends and patterns and link them to the real-world context of the teaching sequence.
When designing a teaching sequence, consider the diagnostic assessment (Launch phase) that identified the alternative conceptions that students held. Are there activities that challenge these ideas and provide openings for discussion? What content knowledge and skills do students need to be able to complete the final (Act phase) task? How could you systematically build these through the investigation routines? Are there opportunities to build students’ understanding and skills in the science inquiry processes through the successive investigations?
Read more about using the LIA FrameworkLocal biomass
Discuss how measuring biomass (the mass of dried renewable organic material that makes up plants and animals) is a way of determining the amount of carbon stored in plants.
- What carbon molecules are there in the plants?
- Genetic material (DNA), proteins, enzymes and sugars .
- What parts of a tree might contain carbon?
- All parts of the tree (trunk, leaves, branches, roots).
- How could we measure the amount of material that there is in a tree?
- What could we measure on a tree that would tell us how big it is?
- Do all trees have trunks?
- No. And some trees have different types of trunks (hard wood trees are more dense than soft wood trees). But we could use it for a guide. Scientists use it for estimates.
(Slide 36) Explain that students are going to measure the biomass of a tree. Provide students with a copy of the Measuring carbon storage Resource sheet. Depending on the number of trees in the school environment, divide students into groups and designate each group a local tree with a base circumference of at least 40 cm.
Agree on a method for each group to distinguish their tree from the others in the area. This can be done by:
- using GPS coordinates.
- taking a photograph.
- drawing its distinguishing characteristics.
✎ STUDENT NOTES: Measure vertically up the trunk, 1.3 m from the base of the tree. This is the height at which you will measure the circumference of the tree. Measure the circumference of the tree (keeping the tape measure level) three times. Determine the average circumference of the tree.
(Slide 37) Use spreadsheet software to prepare a graph of ‘The circumference of the tree (cm)’ vs the ‘Tree’s dry weight (kg)’.
✎ STUDENT NOTES: Use the graph to determine the approximate biomass of the tree that was measured.
Discuss that scientists have tested a large number of trees from across Australia to find patterns and have determined that the tree biomass contains 50% carbon.
✎ STUDENT NOTES: Calculate the total carbon stored in the tree.
$$Total\,carbon\,(tonnes) = total\,biomass\,(tonnes) \times 0.5$$
Discuss how carbon dioxide was taken from the atmosphere as part of photosynthesis.
- How did the carbon get into the tree?
- Where did the tree carbon come from?
- I wonder how much carbon dioxide was taken from the atmosphere by your tree?
✎ STUDENT NOTES: Calculate the amount of carbon dioxide that was removed from the atmosphere through photosynthesis as a result of the tree growing to its current size.
$$Carbon\,dioxide\,equivalent\,to\,biomass = total\,carbon\,(tonnes) \times 3.67 $$
(Slide 38) Optional: Use an algorithm in the data spreadsheet to convert the graph to:
- Circumference of the tree vs Total carbon stored in tree.
- Circumference of the tree vs Carbon dioxide removed from the atmosphere.
Biomass
Biomass is the renewable organism material that is stored in living things.
Biomass is the renewable organism material that is stored in living things. It can be the fuel in a combustion reaction and is often used as a way of measuring the amount of carbon stored in an environment. In general, biomass is made up of approximately 50% carbon.
Most commonly, biomass is a measure of the carbon stored in the plants in the environment. Above Ground Biomass (AGB) is a measure of the dry weight of the tree, including the stem or trunk, bark, branches, leaves, and flowers. To measure the dry weight, all the components of the tree would be dried in an oven until all water had been removed (and the weight no longer changed).
As it is not practical to cut down every tree to measure the AGB, most scientists measure the diameter of the tree truck at 1.3 metres. The relationship between the AGB and the tree diameter will vary slightly depending on the type of tree that is being measured. This is due to trees having different levels of density. Hardwoods grow more slowly and have denser wood than fast-growing trees.
Below-ground biomass (BGB) is the dry weight measurement of all of the roots of a tree. Similar to the Above Ground Biomass, the BGB can be measured using equations specific to individual species. More information can be found in the video Calculating biomass and carbon (4:14).
In this teaching sequence, students will use a simpler calculation of biomass.
Biomass is the renewable organism material that is stored in living things. It can be the fuel in a combustion reaction and is often used as a way of measuring the amount of carbon stored in an environment. In general, biomass is made up of approximately 50% carbon.
Most commonly, biomass is a measure of the carbon stored in the plants in the environment. Above Ground Biomass (AGB) is a measure of the dry weight of the tree, including the stem or trunk, bark, branches, leaves, and flowers. To measure the dry weight, all the components of the tree would be dried in an oven until all water had been removed (and the weight no longer changed).
As it is not practical to cut down every tree to measure the AGB, most scientists measure the diameter of the tree truck at 1.3 metres. The relationship between the AGB and the tree diameter will vary slightly depending on the type of tree that is being measured. This is due to trees having different levels of density. Hardwoods grow more slowly and have denser wood than fast-growing trees.
Below-ground biomass (BGB) is the dry weight measurement of all of the roots of a tree. Similar to the Above Ground Biomass, the BGB can be measured using equations specific to individual species. More information can be found in the video Calculating biomass and carbon (4:14).
In this teaching sequence, students will use a simpler calculation of biomass.
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkFollowing an investigation, the Integrate routine provides time and space for data to be evaluated and insights to be synthesized. It reveals new insights, consolidates and refines representations, generalises context and broadens students’ perspectives. It allows student thinking to become visible and opens formative feedback opportunities. It may also lead to further questions being asked, allowing the Inquire phase to start again.
When designing a teaching sequence, consider the diagnostic assessment that was undertaken during the Launch phase. Consider if alternative conceptions could be used as a jumping off point to discussions. How could students represent their learning in a way that would support formative feedback opportunities? Could small summative assessment occur at different stages in the teaching sequence?
Read more about using the LIA FrameworkValidating the results
(Slide 39) Discuss the results of students’ calculations.
- Why was the circumference always measured at 1.3 m from the ground?
- Why was the circumference of the tree measured 3 times and averaged? How does this affect the accuracy of the results?
- How could we check that the tape measure was accurate? How would it affect our calculations if it was not accurate?
- What would be the largest tree we could measure using this result? Would our results be just as accurate if we used the graph to measure the carbon in a tree larger than 400 cm? Why or why not?
- Extrapolating or extending a graph outside its intended purpose means it is inaccurate.
- Do all trees grow at the same rate? How do you think that this could affect the calculations that we made?
- These calculations assumed that all trees are the same. Some trees are denser than others and therefore may have more or less carbon stored in their biomass.
- How could we improve the accuracy of these measurements? As students? As a scientist working in this area?
- Students could increase the sample size of trees and make comparisons of tree trunks to the height of a tree. Scientists would compare the density of different tree types to compare the biomass stored in slices of a tree.
- What assumptions have we made about this method? How do we know it is a valid test?
Students should write their questions or comments about the validity of their results on sticky notes and place them in a location in the room.
Rearrange the notes into groups and discuss. Use the validity framework as a guide for possible groups:
- Question
- Repeatability
- Assumptions
- Sample size
- Accuracy
- Reliability
- Precision
- Limitations
✎ STUDENT NOTES: Record the factors that contribute to an investigation being valid.
- Do you think this test is valid for all trees in Australia, and in all countries?
- No. Not all trees are the same.
- What does it mean for a test to be valid?
- A valid test can be trusted. It must be repeatable, good sample size, be accurate, reliable, precise, and answer the question that was asked.
- What assumptions have we made about this test?
- The calculations provided by the ‘scientists’ are appropriate for the trees you measured.
(Slide 40) Discuss how biomass could affect the intensity of a bushfire.
- Why is biomass important in bushfires?
- Big trees have more biomass. Dried leaves and bark are also biomass. Biomass is a fuel in a bushfire. More biomass means more fuel.
- Why would small, light leaves and bark be the ‘best’ fuel for a fire?
- They can mix with oxygen easily (like the flour in Lesson 2), thus helping the fire to burn.
- Why do bushfires add to the carbon dioxide levels in the atmosphere in the short term?
- Combustion produces carbon dioxide.
- Why might increasing carbon dioxide levels be a bad thing?
- Might contribute to climate change.
- How could we reduce the number of bushfires?
- This will be covered next lesson.
Reflect on the lesson
You might:
- identify how the intensity of a bushfire is affected by different types of biomass.
- discuss how computer vision and machine learning could be used to determine the biomass of an area.
- re-examine the intended learning goals for the lesson and consider how they were achieved.
- discuss how students were thinking and working like scientists during the lesson.
Validity framework
A framework to assess the validity of an investigation.
There are many things to consider when determining the validity of primary or secondary data. When measuring the biomass of a tree students should consider:
- the reproducibility of the method.
- how the distance of 1.3 m was measured.
- the number of times they measure the circumference of the trunk.
- if any branches or galls (lumps from an infection) affected the measurements.
- if the three measurements were close to each other (precision).
- assumptions made, such as ‘all trees (hardwoods and softwoods) contain the same density of matter’.
- if the method used is one tested by other scientists.
There are many things to consider when determining the validity of primary or secondary data. When measuring the biomass of a tree students should consider:
- the reproducibility of the method.
- how the distance of 1.3 m was measured.
- the number of times they measure the circumference of the trunk.
- if any branches or galls (lumps from an infection) affected the measurements.
- if the three measurements were close to each other (precision).
- assumptions made, such as ‘all trees (hardwoods and softwoods) contain the same density of matter’.
- if the method used is one tested by other scientists.