Physics · 5th Year

Active learning ideas

Forging Elements: Nuclear Fusion

Let's investigate the engine of the stars. This topic unpacks nuclear fusion, the process that powers the sun and offers a tantalising glimpse of a clean, abundant energy future.

• NCCA Curriculum Specifications
• Leaving Certificate Physics Syllabus: Section 4.3 - Nuclear Energy (Fusion)

• 20–45 min
• Pairs → Whole Class
• 3 activities

Activity 01

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• 20 min · Pairs

Fusion vs. Fission Venn Diagram Challenge

In pairs, students complete a Venn diagram comparing and contrasting nuclear fusion and fission. They should include details on fuel, products, energy yield, required conditions, and waste products.

Compare the processes of nuclear fission and nuclear fusion, considering their fuel requirements, products, and energy yield.

Facilitation Tip

Provide a word bank with key terms like 'deuterium', 'uranium-235', 'helium', and 'plasma' to scaffold the activity.

What to look for

Use an exit ticket asking students to write down one key similarity and one key difference between nuclear fission and fusion.

• Understand
• Apply
• Analyze
• Evaluate
• Self-Management
• Relationship Skills

Activity 02

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• 25 min · Small Groups

Magnetic Confinement Marshmallow Model

Using ring magnets and mini-marshmallows, students attempt to build a simple model of a tokamak. The goal is to use the magnetic field to contain the marshmallows (representing plasma) without them touching the sides of a petri dish.

Explain why extremely high temperatures and pressures are essential to initiate and sustain nuclear fusion reactions.

Facilitation Tip

Emphasise that this is a simplified analogy and lead a discussion on its limitations.

What to look for

A structured question on a class test requiring students to explain the conditions needed for fusion and to argue for or against its development as a future energy source, citing specific evidence.

• Understand
• Apply
• Analyze
• Evaluate
• Self-Management
• Relationship Skills

Activity 03

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• 45 min · Whole Class

Future Energy Debate

Divide the class into teams to debate the motion: 'Nuclear fusion is the only viable long-term solution to Ireland's energy needs'. Students must research the pros, cons, and current state of fusion technology.

Evaluate the potential of nuclear fusion as a clean and sustainable energy source for the future, noting the current technological challenges.

Facilitation Tip

Assign specific roles like 'opening speaker', 'rebuttal', and 'researcher' to ensure all students participate.

What to look for

Students use a traffic light system (red, amber, green) to rate their confidence against each of the learning objectives, helping them to identify areas for revision.

• Understand
• Apply
• Analyze
• Evaluate
• Self-Management
• Relationship Skills

A few notes on teaching this unit

Begin by anchoring the concept in the familiar: the sun. Use analogies, like trying to force two powerful north poles of magnets together, to explain the difficulty of overcoming the Coulomb barrier. It is vital to use clear diagrams of the D-T reaction and short video clips of tokamaks in operation to make these abstract ideas tangible. Constantly link the 'missing' mass in the reaction products back to the immense energy released via E=mc².

Following these activities, students will be able to articulate the fundamental principles of nuclear fusion, contrast it with fission, and critically assess its prospects and challenges as a global energy source.

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Watch Out for These Misconceptions

• Nuclear fusion is just another name for the reaction in an atomic bomb.

  The first atomic bombs used nuclear fission (splitting heavy atoms). While hydrogen bombs do use a fission reaction to trigger a much larger fusion reaction, the goal of fusion energy research is to create a slow, controlled, and sustained reaction for power generation, not an uncontrolled, explosive one.

• Fusion reactors will produce the same dangerous, long-lived radioactive waste as fission reactors.

  Fusion's main product is stable helium, which is not radioactive. While the reactor's internal components will become activated by neutrons, this radioactivity is shorter-lived and less hazardous than the spent fuel from fission reactors, which remains dangerous for thousands of years.

• Since fusion happens in stars, it must be easy to do.

  Stars use their immense gravity to crush nuclei together. On Earth, we cannot replicate this gravity, so we must compensate by using even more extreme temperatures, over 100 million degrees Celsius, which presents enormous scientific and engineering challenges.

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Methods used in this brief

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