Average Dependencies Distribution Bar Chart
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An interactive histogram visualizing the distribution of prerequisite counts across all concepts in a learning graph, helping assess the quality and pedagogical structure of concept dependencies.
Interactive Chart
Overview
This bar chart displays how many concepts in a 200-concept learning graph have each number of prerequisites (0 through 8+). The visualization helps educators and instructional designers evaluate whether their learning graph has appropriate complexity distribution.
The chart highlights the optimal range (2-4 prerequisites) where most well-structured concepts should fall, and shows the average prerequisite count across all concepts.
Features
Interactive Elements
- Hover tooltips - Display exact concept count and percentage for each bar
- Smooth animations - Animated bars on page load
- Color coding - Green bars indicate optimal range (2-4), gold bars show other ranges
- Annotations - Visual indicators for optimal zone and average line
Visual Design
- Optimal Range Shading - Light green background highlights the 2-4 prerequisite range
- Average Line - Blue dashed vertical line at 3.1 shows the mean
- Metrics Panel - Six key statistics displayed below the chart
- Analysis Section - Interpretation guidance for understanding the distribution
Interpretation Guide
Key Metrics
- Total Concepts (200) - The complete size of the learning graph
- Total Dependencies (620) - Sum of all prerequisite relationships
- Average Dependencies (3.1) - Mean number of prerequisites per concept
- Median (2) - Middle value when concepts are sorted by prerequisite count
- Mode (2) - Most common number of prerequisites
- In Optimal Range (84%) - Percentage of concepts with 1-5 prerequisites
What Makes a Healthy Distribution
Bell-Curve Shape: The distribution should resemble a bell curve, with most concepts in the middle ranges (2-4 prerequisites) and fewer concepts at the extremes.
Foundational Layer: Having 5-10% of concepts with 0 prerequisites (foundational concepts) provides clear entry points.
Optimal Range: 70-90% of concepts should have 1-5 prerequisites, indicating appropriate granularity.
Few Complex Concepts: Less than 5% of concepts should have 6+ prerequisites to avoid overwhelming learners.
Red Flags
- Flat distribution: Suggests inconsistent concept granularity
- Too many foundational concepts (>15%): May indicate concepts are too broad
- Too many complex concepts (>10% with 6+ prerequisites): Concepts may need to be broken down
- Heavily skewed distribution: Indicates structural issues in the learning graph
Customization Guide
Changing the Data
To modify the chart data for your own learning graph, edit the data array in main.html:
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Updating Metrics
Update the calculated metrics in the HTML to match your data:
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Adjusting the Optimal Range
To change the optimal range shading (currently 2-4), modify the annotation configuration:
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Moving the Average Line
Update the average line position:
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Customizing Colors
Modify the bar colors in the backgroundColor array:
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Technical Details
- Library: Chart.js 4.4.0
- Plugins: chartjs-plugin-annotation 3.0.1 (for shaded zones and lines)
- Browser Compatibility: All modern browsers (Chrome, Firefox, Safari, Edge)
- Dependencies: Chart.js and Annotation Plugin (both loaded from CDN)
- Responsive: Yes, adapts to container width with 2:1 aspect ratio
Calculating Your Own Metrics
To generate these metrics from your learning graph CSV:
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Use Cases
This chart type is useful for:
- Learning graph quality assessment - Evaluate structural balance
- Curriculum design validation - Ensure appropriate complexity progression
- Concept granularity analysis - Identify over- or under-divided concepts
- Pedagogical planning - Plan teaching sequence based on dependency patterns
- Comparative analysis - Compare multiple learning graphs
- Documentation - Communicate graph structure to stakeholders
Lesson Plan
Learning Objectives
After completing this lesson, students will be able to:
- Analyze (Analyze) prerequisite distribution patterns in learning graphs to identify structural strengths and weaknesses
- Evaluate (Evaluate) whether a learning graph has appropriate complexity distribution using quantitative metrics
- Interpret (Understand) statistical measures (mean, median, mode) in the context of educational concept dependencies
- Apply (Apply) optimal range criteria (2-4 prerequisites) to assess concept granularity
- Create (Create) recommendations for improving learning graph structure based on distribution analysis
Target Audience
- Primary: Instructional designers and curriculum developers working with learning graphs
- Secondary: Educators creating structured course content, educational technology specialists
- Level: Graduate-level education programs, professional development for curriculum designers
- Prerequisites: Basic understanding of learning graphs, familiarity with statistical measures (mean, median, mode)
Activities
Activity 1: Identifying Distribution Patterns (15 minutes)
- Examine the bar chart and identify which prerequisite count has the highest number of concepts
- Calculate what percentage of concepts fall within the optimal range (2-4 prerequisites)
- Compare the mean (3.1) with the median (2) - what does this tell you about the distribution shape?
- Discuss: Why might having 12 foundational concepts (0 prerequisites) be appropriate for a 200-concept graph?
Activity 2: Evaluating Quality Using Red Flags (20 minutes)
Using the "Red Flags" criteria from the Interpretation Guide:
- Assess whether this learning graph has too many foundational concepts (check if >15%)
- Check if too many concepts have 6+ prerequisites (should be <10%)
- Evaluate if the distribution resembles a bell curve or is heavily skewed
- Write a 2-3 sentence quality assessment of this learning graph
Activity 3: Comparative Analysis (25 minutes)
- Modify the data array in main.html to create a "problematic" learning graph with:
- 40% foundational concepts (80 concepts with 0 prerequisites)
- Flat distribution across other ranges
- Compare the two visualizations side-by-side
- Document 3 specific ways the problematic graph fails quality criteria
- Propose how you would restructure the problematic graph to improve it
Activity 4: Real-World Application (30 minutes)
- Use the provided Python code to analyze your own learning graph CSV file
- Generate the prerequisite distribution data
- Customize the chart with your data (update the data array and metrics)
- Write an interpretation report addressing:
- Is your distribution healthy? Why or why not?
- What percentage falls in the optimal range?
- What structural improvements would you recommend?
Assessment
Formative Assessment:
- During Activity 1: Can students correctly identify the mode and calculate the optimal range percentage?
- During Activity 2: Do students accurately apply red flag criteria to evaluate graph quality?
Summative Assessment:
Students should demonstrate mastery by completing a practical analysis:
- Data Analysis (30 points): Calculate mean, median, mode, and optimal range percentage from a provided dataset
- Visual Interpretation (30 points): Identify structural issues in 3 different learning graph distributions
- Quality Evaluation (20 points): Write a comprehensive quality assessment using all red flag criteria
- Recommendations (20 points): Propose specific, actionable improvements for a problematic learning graph
Success Criteria: - Students can independently evaluate a learning graph's prerequisite distribution - Students can articulate why 70-90% of concepts should fall in the 1-5 prerequisite range - Students can generate their own distribution charts from CSV data - Students can distinguish between healthy bell-curve distributions and problematic patterns
Extension Activities
- Advanced: Use the Chart.js Annotation Plugin to add custom quality threshold lines
- Research: Investigate how different subject domains (math vs. history vs. programming) might have different optimal distributions
- Collaborative: Compare learning graphs across a cohort and identify discipline-specific patterns