HPU Economics for Hawaiʻi Teachers – Core Concepts & Course Guide

Course Logistics

• 8-week synchronous/recorded webinar (Tue, 3 h); recordings up next morning
• Blackboard: find slides, recordings, quizzes (5 MCQ, 20 min)
  • Quiz 1: Thu–Fri; Quiz 2: Sun–Mon
  • 14 quizzes ➜ best 13 count (one late forgiven)
• Assessments
  • Quizzes 20 %
  • Group lesson plan (draft + revision + video) 30 %
  • Final exam 50 % (≥ $50\%$ to pass)
  • Professional conduct/participation counts
• Groups: ≤ 6 (7 with permission); two live presenters per wk (extra credit); unlimited online submissions wks 3–7
• Use full real Zoom name; chat on-topic; late work = 0 (medical/military docs only)

Graph Refresher

• Axes: vertical $P$ (price), horizontal $Q$ (quantity)
• Positive slope ➜ \frac{\Delta y}{\Delta x}>0 (more x ⇒ more y)
  Negative slope ➜ \frac{\Delta y}{\Delta x}<0 (more x ⇒ less y)
• Steeper line ⇒ larger absolute slope ⇒ stronger effect
• Curves: slope changes along the curve (e.g. accelerating rocket, diminishing returns)
• Horizontal line ⇒ no relationship; vertical ⇒ relationship indeterminate (no x-variation)
• Mnemonic: Diver (D) dives ↓ (demand), Surfboard (S) surfs ↑ (supply)

Demand (Blue)

• Relationship between $P$ and total units buyers would purchase
• Downward-sloping: higher $P$ poisons $Q_D$
• Represents ordered willingness-to-pay (utility) of all buyers
• Impossible to measure exactly—preferences change constantly

Supply (Red)

• Relationship between $P$ and total units sellers would offer
• Upward-sloping: higher $P$ rewards $Q_S$
• Long-run driver = production cost; short-run driver = opportunity cost (best alternative)

Market Equilibrium (Purple)

• $P^<em>$ where $Q<em>D=Q</em>S=Q^</em>$
• Above $P^<em>$ ⇒ surplus (unsold stock) ⇒ price falls Below $P^</em>$ ⇒ shortage (empty shelf) ⇒ price rises
• Acts like marble in bowl: forces (self-interest) push back to $P^*$

Efficiency & Welfare

• At $Q^*$:
  • Highest-valuing buyers get the good
  • Lowest-cost sellers produce
  • No untapped gains (0 dead-weight)
• Producing < $Q^<em>$ ➜ missed trades; producing > $Q^</em>$ ➜ wasteful output
• Markets need costly prices for honest valuation; charity/government can address need when buyers lack funds

Opportunity Cost vs Sunk Cost

• Opportunity cost = value of best foregone alternative (always relevant)
• Sunk cost = irreversible past outlay (irrelevant for future choices)
• Jail example: cost sunk, but future crime prevention justifies action

Price Formation: Need BOTH Demand & Supply

• Water–Diamond paradox: demand for water ≫ diamonds but supplywater ≫ supplydiamonds ⇒ $P<em>{water}<P</em>{diamond}$
• Moon-vs-Mars rock: supplymoon cheaper, yet demandmoon ≫ demandmars ⇒ P{moon}>P_{mars}
• Asking “which side matters more?” is like asking which hand claps

Negative Prices

• Buyer paid to take good (garbage disposal)
  • Starbucks pays you $\$5$ + coffee ⇒ P<0

Quick Equations & Terms

• Straight line: $y=mx+b$ with constant $m$ (slope)
• Surplus: $Q<em>S>Q</em>D$ at given $P$ (sale)
• Shortage: $Q<em>D>Q</em>S$ (stock-out)
• Equilibrium: $Q<em>D=Q</em>S$

Study Tips

• Aim ≈ $50\%$ quiz average; final dominates grade
• Use recordings & dense slides as “textbook” (no paid book)
• Set phone alarms for quiz windows
• Include required econ dictionary definitions in lesson plans