ACARA v9 CONTENT DESCRIPTION “investigate how scientific knowledge is used by individuals and communities to identify problems, consider responses and make decisions”
Builds on what you know about weathering and erosion, where moving water wears away rock and carries off loose sand and soil. Here a whole community uses that science to spot a problem on its own coast, to think through what it could do, and to make a decision together.
A community spots a problem
A small seaside town loves its beach. Families swim there, the surf club trains there and visitors come to walk along the sand. Over the years, though, people notice the beach is getting narrower. The lifeguards measure how far the sand reaches at low tide and write it down each summer. The numbers fall year after year. The town has used careful observation to identify a real problem: the beach is washing away. Now it wants to know why, and what it can do.
From a shrinking beach to a chosen response
Add each new piece of evidence in turn and watch how the community moves from noticing the problem, to understanding it with science, to choosing what to do.
New evidence (1 of 4)
Year after year the lifeguards measure the sand at low tide, and the beach is a little narrower each time.
Accepted model: The problem: the beach is washing away, and the town is losing the sand that people come for.
Add the next piece of evidence and watch whether the accepted model holds or has to change.
Weighing the responses
There is no single perfect cure for a washing beach, so the town lists several responses and weighs each one. Dune grass is cheap and natural but slow to grow. A low rock wall, or groyne, is strong but costly and can starve the next beach of sand. Trucking in fresh sand works at once but does not last. Doing nothing saves money now but lets the beach keep shrinking. Each response gains something and gives something up, so the community thinks about cost, time, the look of the coast and the neighbours before it decides.
Pick a response to the washing beach
You know erosion is moving water carrying off loose sand. Choose a response and see what the town gains and what it gives up.
The beach is washing away and the town must decide what to do. You know that erosion carries off loose sand, and that binding the sand or blocking the waves can slow it. Which response will the community choose?
Choose a response to see what is gained and what is given up.
Which actions really use the erosion science?
Once the town decides to act, it must make sure the work it pays for actually uses the science. The idea is that moving water carries off loose sand, so the response should bind the sand or keep the water from picking it up. Some of the actions below put that idea to work, and some are just about how the beach looks. Sort each one into whether it really uses the erosion explanation.
Does the action use the erosion science to hold the sand?
The science idea: moving water carries off loose sand, so holding the grains or blocking the waves slows the erosion. Decide which actions use that idea.
Claim: Knowing about erosion helps the town slow the washing away of its beach.
They plant dune grass whose roots bind the loose sand so the water cannot carry it off so easily.
They lay down a mat of brushwood that traps blowing sand and lets a new dune build up.
They paint the lifeguard tower a bright new shade of blue.
They place a line of rocks near the water to break the force of the waves before they reach the sand.
They order new flags for the surf club because the old ones look faded.
Decide whether each statement is evidence for the claim, or not.
Why this matters
The dune grass, the rock wall and the brushwood mat all begin with one science idea, that moving water carries off loose sand. A community used careful measuring to spot the problem, used the science of erosion to understand it, and weighed the costs and benefits of each response before it decided. That is what scientific knowledge does for people: it turns a worry on the beach into a problem you can name, explain and act on together.
Quick self-check
1. The town measures the beach and finds it is narrower every year. What problem has the community identified?
2. Science explains that waves and moving water pick up loose sand and carry it off. Which word names that process?
3. Why does the community list several possible responses instead of choosing the first idea?
4. Which choice uses the erosion science to help hold the sand?
5. A fair way to describe how the community reached its decision is: