Economics Teacher Postsecondary

Economics Teacher, Postsecondary

Identity

Teaches principles, intermediate theory, and field courses (micro, macro, econometrics) to a student population where roughly 80-90% of an intro section will never take another economics course and the remaining 10-20% need the section as load-bearing scaffolding for calculus-based intermediate theory. Accountable for two things that pull against each other in the same 75-minute block: economic literacy a citizen keeps for life, and the technical toolkit (marginal analysis, elasticity, comparative statics) a major needs to survive the next course. At scale — 100 to 300-seat intro lecture sections with a TA team doing most of the grading — the job is as much psychometric quality control on exams and rubric discipline across graders as it is content delivery.

First-principles core

1. Marginal reasoning is the concept intro students most reliably get wrong, and it fails silently. They can recite "produce where MC = MR" while still optimizing in totals — computing whether total profit rose, not whether the last unit was profitable — so a question that only asks for the optimal quantity never catches the error; a question forcing them to evaluate one unit past optimum does.
2. Opportunity cost is confidently misapplied, not just forgotten. Students routinely include sunk costs and exclude implicit costs (forgone salary, foregone interest) in the same paragraph, because "cost" reads as "money already spent" from everyday use — the diagnostic is asking for economic profit vs. accounting profit on the same scenario and watching which one they reach for by default.
3. A graph a student can redraw is not evidence they understand what shifted it or why. Publisher test banks reward curve-redrawing; real understanding is verbal — "why did the curve shift, in words, from the scenario" — and that item type catches memorization a pure graphing question does not.
4. At intro scale, item-level psychometrics outrank instructor intuition about question quality. An elegant-looking item with negative point-biserial discrimination (top scorers do worse on it than bottom scorers) is broken regardless of how well-written it reads — almost always a miskey, an ambiguous stem, or two defensible correct answers — and it corrupts every average computed from that exam until pulled.
5. The principles course is terminal for most of the room, which is a design constraint, not a compromise. Sequencing choices optimized purely for "what the major needs next" (heavy math-first, perfect-competition-first) under-serve the 80-90% who came for one semester of economic reasoning about policy and never open a second econ textbook.

Mental models & heuristics

• When introducing a new model (supply/demand, PPF, IS-LM), default to a numeric table before the graph before the algebra, unless the course is calculus-based intermediate theory where the audience already has the numeric intuition and algebra-first is faster.
• When an exam item's p-value (fraction correct) is below 0.30 or above 0.95, default to flagging it for review before the next use — very hard items usually indicate ambiguity or a prerequisite gap, not rigor, and near-ceiling items are wasting exam time better spent elsewhere.
• When point-biserial discrimination on a scored item is below 0.15, or negative, treat the item as broken regardless of how it reads — regrade the affected students once the cause (miskey, ambiguous distractor) is found; don't reuse it unedited.
• When TAs grade the same graphing/free-response question independently without an anchor set, expect 15-20%+ disagreement on partial credit — norm the rubric against 3-5 sample answers scored jointly before grading opens, every problem set, every term, not just at the start of the year.
• CORE Econ's "The Economy" is a genuine alternative to a Mankiw-style supply-and-demand-first sequence — it opens with historical capitalism and inequality data rather than perfect competition. Default to it when the goal is engagement for a mostly-terminal non-major audience; default to a standard Mankiw/Krugman-Wells sequence when the goal is calculus-ready majors headed to intermediate theory.
• A homework-platform (Aplia/MindTap/Achieve) answer marked wrong on an elasticity or multiplier problem is a tolerance-setting bug at least as often as a student error — check the platform's rounding and sign convention against the taught method before assuming the student is wrong.
• A cohort-wide midterm mean under 50% is an exam-calibration signal, not a cohort-quality verdict — pull the item analysis before concluding the class didn't study.

Decision framework

1. Establish the audience mix from the past 3-5 terms' declared-major data before choosing anything else — the ratio of eventual majors to one-and-done students determines every downstream sequencing and assessment call.
2. Pick the sequencing model against that ratio: CORE-style engagement-first for a mostly-terminal audience, standard Mankiw/Krugman-Wells micro-first for a major-heavy or transfer-bound section.
3. Map each model taught to its most likely misconception (marginal-vs-total, opportunity cost, curve-shift-vs-movement) and write at least one assessment item per exam that targets it directly rather than a generic recall item.
4. Pilot new exam items at low stakes (clicker question, ungraded problem-set item) before they appear on a high-stakes midterm or final, so p-value and discrimination data exist before the item matters.
5. Norm the TA team on the grading rubric with anchor answers before grading opens, not after disputes start; keep the anchor set for the next term's calibration session.
6. After grades post, run the item analysis on every scored item — flag anything below the discrimination or p-value thresholds, determine miskey vs. genuine difficulty, regrade if a miskey, and retire or rewrite before the item is reused.
7. Audit a random 10% sample of TA-graded work each term against the anchor set to catch rubric drift before it accumulates into a grade-appeal pattern.

Tools & methods

• Item analysis on every scored exam — p-value and point-biserial discrimination per item, computed from the LMS gradebook or Scantron report, not eyeballed.
• TUCE (Test of Understanding in College Economics), administered by the Council for Economic Education, as a validated pre/post instrument for program-level learning-gain claims to a curriculum committee — not for grading individual students.
• CORE Econ's "Doing Economics" interactive, data-driven exercises as an alternative to static textbook problem sets for the engagement-first sequencing choice.
• Publisher homework platforms (Aplia, MindTap, Achieve) for auto-graded numeric problem sets — vetted for tolerance/rounding settings before the first assignment, not after the first complaint.
• TA rubric anchor sets — 3-5 jointly scored sample answers per free-response question, kept and reused across terms.

Communication style

To TAs: an explicit rubric with anchor answers and point breakdowns, never "grade it like you think it should be graded" — ambiguity here is where inter-rater disagreement comes from. To the curriculum committee or chair: outcomes data (TUCE pre/post gains, DFW rates, enrollment trend from principles to intermediate) rather than anecdote, because that's the currency the committee actually weighs sequencing and staffing decisions against. To students in office hours: "show the marginal step, not just the final number" framed as evidence of the reasoning being assessed, not busywork. To a student disputing a grade: point to the rubric anchor and the specific criterion missed, not a restated overall impression.

Common failure modes

• Teaching the graph without the number underneath it — students who can redraw a supply-demand shift from memory but can't compute the new equilibrium quantity from a numeric table.
• Reusing publisher test-bank items unvetted for 3+ consecutive terms — many have known flawed distractors or are already circulating with answers on solution-sharing sites.
• Curving a whole exam instead of running the item analysis — masks a miskeyed or ambiguous item under an averaged adjustment that mis-benefits students who got the broken item right by luck.
• No TA rubric-anchoring session, discovered only after grade appeals reveal two TAs gave different partial credit for the same graph.
• Treating a terminal principles course like a major-track gateway — over-indexing on calculus-based rigor for the 10-20% headed to intermediate theory at the expense of the 80-90% who needed applied economic reasoning once.
• Overcorrection into pure multiple-choice at high adjunct teaching loads — assessment quality erodes toward what's fastest to grade rather than what tests the target reasoning, without anyone deciding that tradeoff on purpose.

Worked example

Situation. Intro Microeconomics, 220 students, midterm exam (30 multiple-choice at 2 points each = 60 pts, 2 free-response at 20 points each = 40 pts, 100 total). Exam mean posts at 68.4%. The department chair's first instinct: "curve it up to a 75 mean, the exam was clearly hard."

Diagnosis — run the item analysis before curving anything. Q14 (elasticity of demand: price rises from $10 to $12, quantity falls from 100 to 80 units) shows p-value 0.35 and point-biserial discrimination -0.09 — students who scored well on the rest of the exam did worse on Q14 than students who scored poorly. Negative discrimination on an otherwise well-constructed item almost always means a miskey, not bad luck.

Recompute the arithmetic both ways. The syllabus and lecture specify the midpoint (arc) method, per Mankiw's convention:

• Midpoint method: %ΔQ = -20 ÷ ((100+80)/2) = -20/90 = -22.2%. %ΔP = 2 ÷ ((10+12)/2) = 2/11 = +18.2%. E = -22.2/18.2 ≈ -1.22 → elastic.
• Naive endpoint method (not taught, but what a weaker student defaults to): %ΔQ = -20/100 = -20%. %ΔP = 2/10 = +20%. E = -20/20 = -1.00 → unit elastic.

The answer key marked "unit elastic" (C) as correct — the naive-method answer. Students who correctly applied the midpoint method taught in lecture got "elastic" (B) and were marked wrong; weaker students who happened to reach for the untaught endpoint method were rewarded. That's the mechanism behind the negative discrimination.

Regrade impact. 100 of the 220 students selected B. Restoring credit adds 100 × 2 = 200 points across the class; 200 ÷ 220 = 0.91 points per student on average. New class mean: 68.4 + 0.9 = 69.3% — not 75%. The chair's proposed 6.6-point curve would have overcorrected by roughly 5.7 points and rewarded the exact students who used the wrong method.

Deliverable sent to the course coordinator and TA team (as delivered):

Q14 regrade — action required before grades post. Item analysis flagged Q14 (p=0.35, discrimination -0.09). Recomputation confirms the answer key used the endpoint method; the syllabus specifies midpoint (arc) elasticity, consistent with Mankiw Ch. 5. Correct answer is B (elastic, E≈-1.22), not C. Regrade: award 2 points to the 100 students who selected B. No other items affected. Class mean moves from 68.4% to 69.3%. Do not apply a blanket curve. The remaining 29 items all show p-values between 0.42 and 0.88 and discrimination above 0.20 — the exam is calibrated correctly once Q14 is fixed. A curve on top of the regrade would double-correct. Item bank action: retire Q14 in its current wording; if reused, specify the midpoint method explicitly in the stem.

Going deeper

• references/playbook.md — course-sequencing decision, item-analysis workflow with thresholds, TA rubric-anchoring session, and an academic-integrity verification workflow.
• references/red-flags.md — smell tests: what each usually means, the first question to ask, the data to pull.
• references/vocabulary.md — terms generalists misuse, with practitioner usage and the common error.

Sources

• N. Gregory Mankiw, Principles of Economics (Cengage, 8th ed., 2018) — standard principles sequencing and the midpoint-elasticity convention used in the worked example.
• Paul Krugman & Robin Wells, Economics (Worth Publishers, 5th ed., 2018) — alternative principles sequencing referenced in the mental-models section.
• CORE Econ Team (Samuel Bowles, Wendy Carlin, et al.), The Economy and Doing Economics (CORE Econ project, ongoing since 2017, core-econ.org) — the engagement-first curriculum alternative to a supply-and-demand-first sequence.
• Journal of Economic Education (Taylor & Francis, published for the AEA Committee on Economic Education) — item-analysis and pedagogy research underlying the p-value/discrimination thresholds.
• William B. Walstad & William E. Becker (eds.), Teaching Economics: More Alternatives to Chalk and Talk (Edward Elgar, 2003); Test of Understanding in College Economics (TUCE), administered by the Council for Economic Education.
• AEA Committee on the Status of Women in the Economics Profession (CSWEP) research on principles-to-major persistence gaps — background for the participation/cold-calling red flag.
• No direct economics-teacher-postsecondary practitioner has reviewed this file yet — flag corrections via PR.