Show how Big Ideas, Competencies, and Content progress across grade levels for a BC subject. Useful for understanding scaffolding, prerequisites, and learning trajectories. When a query is provided, filters to only matching items at each grade — showing a focused vertical thread rather than a full data dump.
Args:
- subject (string): Subject slug
- grade_from (integer): Starting grade (0=K, 1-12)
- grade_to (integer): Ending grade (0=K, 1-12)
- focus (string, optional): Which element to trace ('big_ideas', 'competencies', 'content', 'all'). Default 'all'.
- query (string, optional): Focus on a specific concept (e.g., 'evidence', 'multiplication'). Only matching items shown at each grade.
Returns: Grade-by-grade breakdown of curriculum elements showing progression, optionally filtered to a concept thread.