Chemistry · Year 12

Active learning ideas

Designing Organic Synthesis Pathways

Active learning breaks down the complexity of organic synthesis by making abstract multi-step pathways concrete. Students engage directly with reagents, conditions, and intermediates, which builds confidence in planning reactions they once viewed as theoretical. Hands-on activities replace passive note-taking with iterative problem-solving, reinforcing ACSCH138’s emphasis on transformation and evaluation.

• ACARA Content Descriptions
• ACSCH138

• 30–50 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Jigsaw
• 50 min · Small Groups

Jigsaw: Building Pathways

Divide reactions into types like substitution and addition; each small group masters one and creates cards with reagents, conditions, and products. Groups then reassemble to design a full pathway for a target like ethyl ethanoate, trading cards as needed. Conclude with presentations.

Identify appropriate reagents and conditions for common organic transformations.

Facilitation Tip

During Retrosynthesis Jigsaw, assign each group a different target molecule so they can compare approaches and learn from varied examples.

What to look for

Provide students with a simple target molecule (e.g., ethyl acetate) and two simple precursors (e.g., ethanol and acetic acid). Ask them to write down the specific reagents and conditions needed to synthesize the target molecule in one step, and identify the type of reaction.

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

Activity 02

• Problem-Based Learning
• 30 min · Pairs

Pathway Relay Race: Step-by-Step Synthesis

In pairs, students start with a precursor and add one reaction step per turn, passing to the next pair for continuation toward the target. Include constraints like atom economy. Pairs defend their final route against class feedback.

Design a plausible multi-step synthesis for a simple organic molecule from readily available precursors.

Facilitation Tip

In Pathway Relay Race, set a visible timer and rotate groups every two minutes to keep energy high and prevent over-analysis.

What to look for

Present two different synthesis pathways for the same target molecule. Ask students to discuss in small groups: Which pathway is more practical? Consider factors like the number of steps, availability of reagents, and potential side reactions. Each group should present their chosen pathway and justify their reasoning.

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Activity 03

• Problem-Based Learning
• 40 min · Small Groups

Route Comparison Cardsort: Evaluation Challenge

Provide cards for two synthetic routes to the same product; small groups sort them by steps, reagents, and hazards, then rank based on yield and safety data. Discuss green chemistry principles in debrief.

Evaluate different synthetic routes based on practicality, yield, and safety considerations.

Facilitation Tip

For Route Comparison Cardsort, pre-print hazard icons and cost labels so students must align these constraints with reaction types during sorting.

What to look for

Give students a diagram showing a two-step synthesis pathway with reagents and conditions indicated. Ask them to identify the starting material, the intermediate, and the final product, and to briefly explain the purpose of the second reaction step.

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Activity 04

• Problem-Based Learning
• 45 min · Pairs

Molecular Model Build: Visual Pathway

Individuals or pairs use ball-and-stick models to construct precursors and snap on functional groups for each step. Photograph the sequence and annotate with conditions. Share digitally for class vote on best route.

Identify appropriate reagents and conditions for common organic transformations.

Facilitation Tip

During Molecular Model Build, provide only single bonds initially, then challenge students to convert them to double or triple bonds in later steps.

What to look for

Provide students with a simple target molecule (e.g., ethyl acetate) and two simple precursors (e.g., ethanol and acetic acid). Ask them to write down the specific reagents and conditions needed to synthesize the target molecule in one step, and identify the type of reaction.

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

A few notes on teaching this unit

Experienced teachers approach synthesis design by balancing rigor with iterative practice. They avoid overwhelming students with too many reagents at once, instead focusing on one reaction type per activity before combining them. Research shows that students retain synthesis planning better when they physically manipulate models or cards than when they only write pathways. Teachers also model their own thinking aloud during planning, demonstrating how to weigh yield, cost, and safety in real time.

By the end of these activities, students will confidently design two or more synthesis pathways for a given target molecule, justify their choices with yield calculations and safety considerations, and revise routes based on peer feedback. They will also recognize that the shortest path is not always the best path.

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Watch Out for These Misconceptions

• During Retrosynthesis Jigsaw, watch for students who insist their pathway is the only correct one because it has fewer steps.

  During Retrosynthesis Jigsaw, have groups calculate overall yield for their pathways and present this data in a gallery walk. Force comparison with other groups’ yields to highlight that efficiency matters more than step count.

• During Molecular Model Build, students may assume any reagent can be used regardless of functional groups.

  During Molecular Model Build, give each group a set of colored blocks representing interfering groups. Ask them to physically block or alter these groups before adding reagents, making incompatibilities visible and discussable.

• During Route Comparison Cardsort, students may ignore safety and waste concerns.

  During Route Comparison Cardsort, provide hazard charts and atom economy data alongside reaction cards. Require groups to sort routes first by yield, then by safety and sustainability before finalizing their choice.

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Methods used in this brief

• Jigsaw
• Problem-Based Learning