Computing · JC 1

Active learning ideas

Entity-Relationship (ER) Modelling

Students often struggle to visualize how data connects across tables, so active learning breaks the abstraction into tangible steps. Working through ERD challenges and normalization exercises lets them see why relationships matter, making the shift from flat files to structured databases feel purposeful rather than abstract.

• MOE Syllabus Outcomes
• 9569 4.2.1 Draw ER diagrams for given scenarios
• 9569 4.2.2 Resolve many-to-many relationships using a link entity

• 20–50 min
• Pairs → Whole Class
• 3 activities

Activity 01

• Inquiry Circle
• 50 min · Small Groups

Inquiry Circle: ERD Design Challenge

Groups are given a scenario, like a 'Grab-style' ride-hailing app. They must identify the entities (Drivers, Riders, Trips) and their attributes, then use large sheets of paper to draw the relationships and cardinalities between them.

How do we identify entities and attributes from a scenario?

Facilitation Tip

During the ERD Design Challenge, circulate and ask groups to explain their entity choices aloud before sketching relationships, reinforcing the habit of verbalizing design decisions.

What to look for

Provide students with a small 8x8 pixel grid and a limited 4-color palette. Ask them to draw a simple smiley face and then write the binary code for the color of one pixel and its coordinates (e.g., Pixel (3,5) is color 01).

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Activity 02

• Stations Rotation
• 45 min · Small Groups

Stations Rotation: The Normalization Hospital

Set up stations with 'sick' (un-normalized) tables full of redundant data and update anomalies. Students must 'cure' the tables by breaking them down into 1NF, 2NF, and 3NF, explaining their reasoning at each step.

How are relationships represented in an ER diagram?

Facilitation Tip

For The Normalization Hospital, assign roles so one student updates the flat table while another updates the normalized one simultaneously, making the contrast visible.

What to look for

Pose the question: 'Imagine you are designing a new global messaging app. Which character encoding would you choose and why? What are the potential problems if you chose the other main option?' Facilitate a class discussion comparing ASCII and Unicode for this scenario.

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

Activity 03

• Think-Pair-Share
• 20 min · Pairs

Think-Pair-Share: Real-World Relationships

Students think of a many-to-many relationship in their school life (e.g., Students and Subjects). They pair up to discuss why a 'junction table' is necessary to model this in a relational database and what data that table should hold.

How do we resolve many-to-many relationships?

Facilitation Tip

Use Think-Pair-Share to have students debate real-world relationships first, then refine their ERD drafts with peer feedback before finalizing.

What to look for

Show students two images of the same graphic: one a high-resolution bitmap and one a scalable vector graphic. Ask them to identify which is which and explain one key difference in how they would scale or be stored, based on their properties.

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

A few notes on teaching this unit

Teach ERDs by grounding them in familiar systems students have encountered, like school databases or social media apps. Avoid overwhelming them with jargon, and instead focus on modeling one relationship at a time. Research shows that students grasp normalization better when they experience the pain of redundancy firsthand, so simulations work more effectively than lectures for this topic.

Successful learning looks like students designing accurate ERDs with clear relationships, normalizing tables to eliminate redundancy, and explaining their choices with confidence. They should articulate why primary keys must be unique and how normalization prevents update errors in real systems.

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Watch Out for These Misconceptions

• During the ERD Design Challenge, watch for students who try to combine all data into one large table for simplicity.

  Guide them to split data into separate entities and define relationships explicitly, using the activity's requirement to model a real-world system like a school or store.

• During the Think-Pair-Share activity, watch for students who select names as primary keys in their ERDs.

  Have peers review their drafts and challenge them to explain why names are unreliable keys, then prompt them to substitute a unique ID like a student ID or product code.

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Methods used in this brief

• Inquiry Circle
• Stations Rotation
• Think-Pair-Share