Designing an icebreaker
In this learning sequence, explore the science carried out on icebreakers and how icebreakers are designed. Find out how scientists and engineers use scale models, water tanks and ice tanks to design and test real ships. Design your own ice tank and model ship, plan and conduct experiments and learn about the forces involved in breaking ice at sea.
Setting the scene
Pose the questions: Why does Australia need a new icebreaker? What do Australian scientists study on the icebreaker? What are some of the benefits of this research?
Split the class into five small groups and have each group read a section about the ship of the future.
- Group 1: Deck space, winches and lifting equipment
- Group 2: Side and moon pool deployments
- Group 3: Noisy science
- Group 4: Ice platform
- Group 5: Cargo capacity
Each group should read through the article together and record:
- words that are new or that they don’t understand. Encourage them to have a go at working out the meaning from the article context, and pencilling in a suggested meaning to discuss with the whole class.
- science research activities that are mentioned. Encourage them to discuss whether they know/understand what the science activity involves so they can share back with the class.
Explain that there are lots of words/activities in the article that may be new to them, and the idea is to learn what they are together – it’s not a test!
Ask each group to report back their new words: amalgamate their responses and record discussion to create a whole class list of new terms. Use prior knowledge from other students and groups to help fill gaps. Acknowledge if there are words that no one knows. These can be researched separately (there may be volunteers for this).
After the new terms, ask groups to share the research activities that were mentioned in their section of the article. List these out, highlighting any that are new to the class.
Ask students what the main ‘branches’ are of science – eg: Chemistry, Biology, Physics, Geology and so on. Then as a class, classify the science activities that are taking place on the icebreakers according to the branch(es) of science. It’s okay if some of this is initially just guesses – the important part is the discussion, and that they see the breadth and importance of the research happening on the vessel.
Extension: Have students select one of the activities that interest them, find out more and present to the class.
Explore and research
Pose the question: What is an icebreaker anyway?
In southern waters, ice sheets can be a metre or more thick. Icebreakers are designed so that the front of the ship curves under, allowing the ship to push the ice sheet downwards as the ship moves forward.
The new icebreaker will be faster and stronger than the Aurora Australis, but what does that mean?
Show the students the icebreaker capabilities and discuss, in particular, the speed and ice thickness capabilities of the new vessel. Draw students attention to the ice thickness: is anyone in the class 1.65 metres tall? Have the class imagine that thickness of ice floating on water. Relate back to how the icebreaker works by pushing down on the ice as it moves forward.
What do the class know about ice and in particular ice in Antarctica? Conduct some of the experiments and activities on the sequence of water, snow and ice if there is time.
Elaborate and apply
The extreme conditions in southern waters make it difficult to design ships at full scale, so scientists and engineers make models. But a tiny ship can’t break through 1.65 metres of ice, so the ice thickness is scaled down to match. These model ships are then sailed on huge water tanks and ice tanks to simulate being at sea. It’s much easier to tweak the design of a model if needed, before building a huge ship.
Give students access to specifications of an icebreaker. How long is the new icebreaker? How long would a 1:100 model be? How thick is the ice being broken? How thick is this ice at 1:100?
Discuss this with students, asking them to indicate how big this is using everyday objects.
Explain that even this is tricky, as a scaled down ship may be 1/100th as heavy, but scaled down ice is more than 1/100th as strong – it’s still too strong for a small ship to break. Icebreaker designers use substances other than ice to simulate the ice sheets.
Activity: designing simulated ice
Ask students to list the important properties of ice that a replacement substance would need to simulate ice in an ice tank, for example floats on water, has a breaking strength less than ice, is solid or semi–solid at temperatures used for testing. Have the class brainstorm some suggestions for a substance that fits the bill, for example butter, copha, wax, pieces of bubble wrap, etc.
Design and test an ice tank and icebreaker. Guide students to design and conduct their own ice tank experiment. This activity will extend over several lessons as students will need time to plan, gather their equipment, prepare their ice sheet, and conduct their tests, including multiple iterations as they refine their design.
This should be an open-ended investigation that encourages students to predict, observe, explain, to make hypotheses and test them, to repeat their design and to communicate what they discover with appropriate audiences.
Notes to help guide student thinking
Students will need support in deciding what scale to conduct their experiment at. To make a very small scale ice tank and icebreaker, consider a scale around 1:1000 or 1:500. This will give a model icebreaker of around 15–30 cm, a good size for using an ice cream container as an icebreaker. Many ice cream containers curve under gently on the sides, making for an ideal icebreaker prow. The ice cream container can be loaded with weight to match the scale weight.
Students may want to try a number of different surfaces to simulate ice, and this will take time to set up and test. They may need access to a refrigerator and freezer. They will need to scale down the ‘ice’ thickness and may need some help thinking through what that means in terms of the amount of substance required, and testing at different thicknesses.
Students will need a small, shallow tank to test their surface and model ship. Depending on the scale they choose, a large baking dish, clean kitty litter tray or similar may work. This tray may need to fit in a refrigerator or freezer to ‘set’ the ice sheet.
An ice cream container may make a good model icebreaker – but students may wish to be more creative with their model depending on time allowed. The model will need to be able to float, to bear a load, and to be able to be towed or pushed in a controlled way across the surface of their tank. Students may need help in identifying the forces at work here, and how the model being pulled forward results in the ice breaking. Encourage them to draw what is happening, including the forces on the boat as it moves, including gravity, and show how this results in forces pushing down on the ice.
Aims and hypotheses
Encourage students to consider what their experimental aims and hypotheses are before they start. Then they can make thoughtful predictions and observations with this in mind.
- Aim: to test different ice simulations to discover the best one (‘best’ can then be discussed and defined)
- Hypothesis: butter will be a useful substitute for ice sheets at a 1:500 scale model tank
As they iterate their experiment, their aims and hypotheses may change – this is how scientists and engineers work.
Guide students to record their questions, predictions and observations in a systematic way. As their investigation progresses, encourage them to discuss their findings with other students. Consider using photographs and video as records of the investigation. At the conclusion of the process, ask students to consider how they will bring all of their findings together to a conclusion, and communicate this with others. This design process would lend itself well to them making a mini documentary of their predictions, design steps, observations and final product.
At various points in the learning assess to what extent students:
- predict and explain the effects of balanced and unbalanced forces
- describe their understanding of forces using scientific language, drawings, diagrams
- describe how motion, forces and energy are used in their design of their icebreaker and ice tank
- describe how the materials they chose and the characteristics of the materials form part of their design solution
- describe how scientists across multiple disciplines work together to develop new understandings
- plan an experiment to test a hypothesis and identify variables to be measured
- explain their predictions and why their results varied from what they expected
- summarise and describe the results of their experiments and communicate their ideas to an audience.