1.2 Systems and modelsMonday, October 26, 2015

Scott Lucas

Dwight School London, 2015

Assessment statements

Significant ideas

• A systems approach can help in the study of complex environmental issues.

• The use of systems and models simplifies interactions but may provide a more holistic view without reducing issues to single processes.

Knowledge and understanding

• A systems approach is a way of visualizing a complex set of interactions which may be ecological or societal.

• These interactions produce the emergent properties of the system.

• The concept of a system can be applied at a range of scales [Biosphere refers to the part of the Earth inhabited by organisms thatextends from the upper parts of the atmosphere to deep within the Earth’s crust.]

• A system is comprised of storages and flows.

• The flows provide inputs and outputs of energy and matter.

• The flows are processes that may be either transfers (a change in location) ortransformations (a change in the chemical nature, a change in state or a change inenergy).

Knowledge and understanding

• In system diagrams, storages are usually represented as rectangular boxes andflows as arrows, with the direction of each arrow indicating the direction of each flow. The size of the boxes and the arrows may be representative of thesize/magnitude of the storage or flow.

• An open system exchanges both energy and matter across its boundary while aclosed system exchanges only energy across its boundary.

• An isolated system is a hypothetical concept in which neither energy nor matter is exchanged across the boundary.

• Ecosystems are open systems; closed systems only exist experimentally, although the global geochemical cycles approximate to closed systems.

• A model is a simplified version of reality and can be used to understand how asystem works and to predict how it will respond to change.

• A model inevitably involves some approximation and therefore loss of accuracy.

Applications and skills

• Construct a system diagram or a model from a given set of information. [Students should interpret given system diagrams and use data to producetheir own for a variety of examples, such as carbon cycling, food production and soil systems.] [Students are not expected to know any particular system diagram symbols such as those of Odum or Sankey.]

• Evaluate the use of models as a tool in a given situation, for example, climatechange predictions.

International-mindedness

• The use of models facilitates international collaboration in science by removing language barriers that may exist.

Vocabulary

• System: • Model: • Storages: • Flows:• Inputs: • Outputs: • Energy: • Matter:• Transfers: • Transformations:

Significant idea (SI1.2.1): A systems approach can help in the study of complex environment issuesU1.2.1 A systems approach is a way of visualizing a complex set of interactions which may be ecological or societal

• The environment is a set of systems that interact

• Scientists develop models to show the interactions between each component in a system

• By nature, models involve simplification of the system• A 1:1 model would be as complex as the system itself; a

bit like having a 1:1 city map, the map would be as large as the city itself

• Other systems interact with the environment• Economic, societal, political, etc.

Significant idea (SI1.2.1): A systems approach can help in the study of complex environment issuesU1.2.1 A systems approach is a way of visualizing a complex set of interactions which may be ecological or societal

• Abstract or tangible systems are represented using diagrams

• Systems interact and exchange inputs and outputs of matter and energy (living systems); or information (non-living systems)

U1.2.2 These interactions produce the emergent properties of the system

• A systems is more than the sum of its parts

• A computer is more than a bunch of metals and plastic

U1.2.3 The concept of a system can be applied to a range of scales• A system can be

• Living or non-living

• On a range of scales, examples include• A cell, you, a bike, a car, your home, a pond, an ocean, a smart

phone, a farm, Earth, etc

• Open, closed or isolated; though most are open including living systems

• Ecosystems are on a range of scales• A drop of pond water, an ocean; a tree, a forest; a coral reff to

an island; a biome or the biosphere

U1.2.4 A system comprises of storages and flowsU1.2.5 The flows provide inputs and outputs of energy and matter

• Storages are where energy or matter remains as stock or storages

• Flows are where energy or matter move between storages (inputs and outputs)

U1.2.6 The flows are processes and may be either transfers (a change in location) or transformations (a change in chemical nature, a change in state or a change in energy)

• Matter and energy flow (move) through ecosystems as• Transfers (change in location)

• Water from river to ocean

• Chemical energy of animal being eaten by another animal

• Ocean currents carrying heat

• Transformations (change in state)• Matter to matter: glucose to starch, solid to liquid to gas

• Energy to energy: light to heat by radiating surfaces

• Energy to matter; light energy to chemical energy (photosynthesis)

• Matter to energy: combustion

U1.2.7 In system diagrams, storages are usually represented as rectangular boxes, and flows as arrows with the arrow indicating the direction of the flow. The size of the box and the arrow may represent the size/magnitude of the storage or flow.

Energy and matter exchange in an immature forest

Task: Construct a model of your home with storages and flows

Types of systems

• Three types: Open, Closed and Isolated

1. Open: exchanges energy and matter with its surroundings

2. Closed: exchanges energy but cycles matter

3. Isolated: exchanges neither energy nor matter

U1.2.8 An open system exchanges both energy and matter across its boundary while a closed system only exchanges energy across its boundaryU1.2.10 Ecosystems are open systems. Closed systems only exist experimentally although the global geochemical cycles approximate to closed systems

• Open: exchanges energy and matter with its surroundings• For example: a forest ecosystem

• Plants fix light via photosynthesis

• Air nitrogen is fixed by soil bacteria

• Herbivores may graze in other ecosystems i.e bordering grassland

• Forest fires expose soil to erosion

• Minerals are leached by rain and water

• Water is lost is evaporation and transpiration

• Heat is exchanged with surrounding environment

U1.2.8 An open system exchanges both energy and matter across its boundary while a closed system only exchanges energy across its boundaryU1.2.10 Ecosystems are open systems. Closed systems only exist experimentally although the global geochemical cycles approximate to closed systems

• Closed: exchanges energy but cycles matter• Extremely rare in nature

• Hydrological, carbon and nitrogen cycles

• Earth is an “almost” closed system• Energy: Light energy enters and heat energy is radiated

• Matter: very small amount of exchange; meteors and satellites

• Artificial closed systems include experiments and sealed aquariums/terrariums eg. Bottle Garden• Don’t typically survive long as they become unbalanced eg.

Biosphere 2

• Life in Biosphere 2 (TED Talk)

U1.2.9 An isolated system is a hypothetical concept in which neither energy not matter is exchanged across the boundary

• Isolated: exchanges neither energy nor matter

• Do not exist naturally, hypothetically the universe is an isolated system

Summary

System Energy exchanged? Matter exchanged?

Open

Closed

Isolated

System Energy exchanged? Matter exchanged?

Open Yes Yes

Closed Yes No

Isolated No No

SI1.2.2: The use of models of systems simplifies interactions but may provide a more holistic view than reducing issues to single processesU1.2.11 A model is a simplified version of reality and can be used to understand how a system works and predict how it will respond to changeU1.2.12 A model inevitably involves some approximation and loss of accuracy

• Scientists use models to understand a system and predict the result of changes in the system

• Models have limitations as they, by nature, are simplified so they don’t account for all interactions

• Hard to make models accurate as all the interactions/rules may not be known/understood, or omitted for simplicity

• A model can be: • physical, a wind tunnel, solar system model,

aquarium/terrarium• software, model of climate change or evolution• Mathematical equations• Data flow diagrams

SI1.2.2: The use of models of systems simplifies interactions but may provide a more holistic view than reducing issues to single processesU1.2.11 A model is a simplified version of reality and can be used to understand how a system works and predict how it will respond to changeU1.2.12 A model inevitably involves some approximation and loss of accuracy

• Strengths• Easier to work with than complex reality• Can be used to predict the effect of change of input• Can be applied to other similar situations• Help us see patterns• Can be used to visualize really small things (atoms) and really

large things (solar system)

• Weaknesses• Accuracy is lost due to simplification• If assumptions are wrong, the model is wrong• Predictions may be inaccurate• “Models are only as good as the rules used to create it” (BBC

Bitesize)

Gaia model (pg 25)

• In 1979, James Lovelock published a theory about the Earth as an organism, one large system composed of smaller systems and components

• Feedbacks, predominantly negative (see 1.3), regulate things such as• The temperature of Earth’s surface

• The composition of the atmosphere

• The ocean’s salinity

S1.2.1 Construct a system diagram or a model from a given set of information

S1.2.2 Evaluate the use of models as a tool in a given situation, eg for climate change predictions

Task: complete the systems

Burning candle

Boiling kettle A plant Animal population

Inputs

Outputs

Transfers

Transformations

Visit ProjectEd for more resourceshttps://sites.google.com/a/dwightlondon.org/projected/

Works Cited

• International Baccalaureate Organization. Diploma Programme Environmental systems and societies guide. The Hague: IB Publishing Ltd, Feb. 2015. PDF.

• "Modelling with Spreadsheets." BBC News. BBC, n.d. Web. 13 Aug. 2015. <http://www.bbc.co.uk/schools/gcsebitesize/ict/modelling/0spreadsheetsrev5.shtml>.

• Rutherford, Jill. Environmental Systems and Societies. Oxford: OUP, 2015. Print.