Assess students' ability to analyze simultaneous supply and demand shifts in a local bicycle market after a safety recall (reducing supply) and a summer-driven demand increase: identify and compare the direction and relative magnitude of shifts, determine likely effects on equilibrium price and quantity (including ambiguous vs. unambiguous outcomes), interpret and draw supply–demand graphs, and solve a simple numerical example using linear equations; scope limited to qualitative comparative statics and basic algebra appropriate for middle school.