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How to design and plan an interdisciplinary PBL unit

Interdisciplinary learning is a growing trend within secondary schools around Australia. It is increasingly uncommon for a school not to have at least part of the curriculum for one subject co-joined with another. For some schools, this is easily tackled through a STEM program; for others, the subject combinations which are grouped together are more bespoke. In every case, however, project-based learning (PBL) is a powerful vehicle through which interdisciplinary learning can be delivered in an authentic and engaging way. In this edition of the eduSTEM Review, we extend on the approach taken by Rachael Patrick at Loyola College to outline best practices for how to go about planning and structuring a cross-curricula unit at your school.

Why embrace interdisciplinary learning?

There are three key reasons for schools to adopt interdisciplinary learning.

The first is quite simply that life is interdisciplinary and does not conform to the rigid compartmentalising of knowledge that has for so long prevailed in secondary schools and at universities. Real world problems rarely arise within orderly disciplinary categories, and neither do their solutions. Once outside the confines of secondary education, students will quickly realise that navigating the world around them will require them to draw upon knowledge from different subject areas or domains. To do this, students must become adept at pattern recognition; they must be able to identify, in a given scenario, which elements of knowledge are needed and how to layer and synthesise them to solve a problem or produce a solution. This is a skill best learned throughout secondary school, where students can be given problems requiring them to draw upon knowledge learned from multiple disciplines.

Interdisciplinary learning isn’t just about setting students up for success later in life, however; it also promotes deeper thinking around the content they are learning in each subject. By creating a context where a real-world problem can only be solved through the application of knowledge from different disciplines, students must manipulate this knowledge in new ways and transfer their understanding of theoretical constructs to a new paradigm. The ability to apply curriculum content in this way both consolidates and deepens student comprehension and, by connecting ideas from different disciplines, retention of what has been learned is strengthened through the reinforcement and multiplication of neural networks.

The final benefit of interdisciplinary learning is one which Rachael Patrick, Head of Humanities at Loyola College, alludes to in her reflection of implementing PBL. In a crowded curriculum, where each subject is vying for more class time to cover a sprawling range of content, it can be more efficient for subjects to work together to address multiple content areas through the same unit. Similar topic areas are often covered in different subjects in slightly different ways when it would be more efficient – as well as more effective for student learning – if they were grouped together. Teachers will be familiar with the refrain from students – ‘Haven’t we already done this before?’ – which accompanies the realisation that a topic about to be embarked on in Geography has been touched on to some extent in Science. By grouping similar topics together, teachers can avoid this problem and free up more time for themselves to go deeper into the content.

How to plan an interdisciplinary unit

First, a word of caution on the common pitfalls schools can fall into when planning an interdisciplinary unit.

Interdisciplinary learning is often invoked as a justification to squeeze multiple subjects into a unit of study, regardless of how organically each subject fits together as part of that unit. This frequently leads to additional subjects being ‘bolted on’ to the unit, with the result that the learning experience of the other subjects is not enhanced. A good rule to follow is that a subject should only be included in an interdisciplinary unit if the application of that subject’s content will either improve the solution students are working towards or will enhance their understanding of all other subjects in that unit.

In the same vein, going too broad too quickly is a common challenge schools face and is often why interdisciplinary projects can come slightly off the rails. Translating initial enthusiasm around interdisciplinary learning into a unit spanning four or five faculties is exciting and admirable, but it is akin to building a skyscraper without a stable foundation. Interdisciplinary learning is new for many staff and students and is more complex to deliver, due to the dependencies between subjects, than delivering content within siloed faculties. A more prudent strategy is to start small and initially attempt an interdisciplinary unit spanning no more than two subjects. This makes it easier to plan and deliver and eases the cognitive strain on students as they adapt to a new way of thinking. Should this succeed – which it is more likely to – schools can consider gradually growing the number of subject areas they integrate into a given unit.

With those caveats in mind, we suggest taking the following approach to planning an interdisciplinary unit:

1. Identify content commonalities. Bring curriculum leaders together and do a broad survey of the topics taught each subject area. You may find some content areas complement each other perfectly; like, for example, the Water in the World Geography unit and the Science content areas on renewable and non-renewable resources. This happens more often than one might think across the curriculum; where such a close match exists, these subjects are perfectly suited to be paired together in an interdisciplinary unit

2. Choose a lead subject and content area. For some subjects or content areas, there is no clear crossover with the content in another subject. When this occurs, a lead subject and content area should be chosen which will anchor the interdisciplinary unit. This choice should be made based on a real-world problem or context which would make for an interesting project and the subject which best lends itself to that problem.

For example, if ocean plastic waste is chosen as the focus of the unit, Science might be chosen as the lead subject. This is because different Science topics lend themselves well to that real-world problem, whether it is investigating the impact of the plastic on marine ecosystems or assessing the chemical composition of plastic to understand why it doesn’t biodegrade. Once this decision is made, the topic area within Science that is applied to the unit will determine from which angle students examine the problem, which in turn influences the type of solution they will be working towards.

3. Choose a supporting subject. If the lead subject is to anchor the project, the supporting subject must either bring in content which fleshes out the students’ understanding of the problem or which helps them ideate and develop a solution to that problem. Though content from that supporting subject might not inherently lend itself to the problem of ocean plastic waste like Science, our lead subject, it must introduce concepts that are necessary to solve the problem in the real-world.

For example, if students analyse the impact of ocean plastic waste on marine ecosystems through Science, Maths concepts could be introduced to help students quantify that impact through the application of indices, percentages, or linear relationships. Alternatively, algebra could be introduced to help students’ model and predict the movement of plastic in the ocean due to ocean currents, which helps them better identify which marine ecosystems will be hit harder than others. This is important information if students are to devise a solution to protect a specific ecosystem or species.

4. Define the duration of each subject in the project. An interdisciplinary unit does not necessitate each subject contributing content from start to finish. One subject can help a student understand a problem, whilst another subject can give them the skills to solve that problem later in the project. As an example, if students assess the chemical composition of plastic in Science to understand the problem (why it doesn’t biodegrade), design & technology content could be introduced to help students design and produce a biodegradable plastic replacement, and English content (in the form of persuasive language and writing techniques) could be introduced as students are tasked with ‘selling’ their new invention. Here, whilst Science was relied on at the start of the unit, students will need to continue drawing on those concepts when they define a solution, marrying that theoretical base with the skills required from other subjects to create an output.

How to deliver an interdisciplinary unit

Once an interdisciplinary unit is planned, effectively facilitating it also presents its own challenges. These simple strategies can help keep your unit (and students) on track.

1. Parallel or dependency model? You can choose to deliver an interdisciplinary unit in one of two ways.

The first is what we call the parallel model; here, the subjects involved in the project are taught in separate ‘streams’, where what happens in one subject isn’t then dependent on what happens in another subject, until the point where students must bring subject knowledge together to create a solution. This is suited to a project where the subjects involved provide content which helps a student understand the problem they must solve, and where the creation of a solution requires the blending of that knowledge. It is also less complex, as the project can progress in one subject even if progress in another subject has been disrupted.

The second delivery model is what we call the dependency model. This creates a project where what happens in one lesson depends on the progress that was made in a previous lesson. It involves structuring the task sequence of the project so that the content of one subject feeds into the other, which then feeds back into the first subject, in a step-like fashion. This format does lead to a greater level of integration between the different subjects – they are dependent on each other – but it does make it harder to plan and it is more likely to come unstuck. All it takes is for one lesson to run behind time or for a class to be missed due to an excursion and the entire sequence can get thrown out of alignment.

Our recommendation is to adopt the parallel model, with a clearly defined point at which the two separate subjects will converge and become one common vehicle for the project. This should only occur after all relevant content from that subject has been taught and introduced into the project.

1. Share domain expertise. A common fear for teachers running an interdisciplinary unit is that they will have to ‘teach’ content from another discipline, or help students apply that content, when the teacher themselves might not fully understand it. This should largely be avoided through the adoption of the parallel model – as each teacher is confined to their domain of expertise while content is being actively taught or introduced – but students may have domain-specific questions when applying that content in the solution stage, by which time classes from both subjects are being used for that purpose. To ensure teachers from both domains know enough to help guide students, teachers should share their expertise. Each faculty should put on a short masterclass for the other, where they explain key concepts, show how they are applied to the project, and provide teachers with the chance to actively apply those concepts to the project like a student would.

2. Create structures and routines to share information. A common refrain amongst schools is that teachers from different faculties are ‘siloed’ and don’t frequently communicate with each other. This can be the death of an interdisciplinary project. Information must flow consistently between teachers from different faculties around student progress, how well different teams are collaborating, and the ideas teams are working on and how they might need to use different content elements to bring them to life. Before the project starts, teachers should create a common space where this information can be shared and should agree on protocols for what information should be shared and how regularly (after each class? Twice a week) it should be shared.

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