Labor Market Classroom Activities Built Around One Graph

A labor market activity earns its period when a student has to make a hiring decision, not just label a curve. Below are seven activities for AP Microeconomics built around the interactive graph at /sandbox/factor-markets, each with a timing, the mechanics, the debrief question, and the misconception it breaks.

Labor demand is not ordinary demand. It is a derived demand: a firm wants a worker only for the extra revenue that worker generates, marginal product times the price of what the worker helps produce. A textbook states the hiring rule, hire while marginal revenue product is at least the wage, in one sentence. Only an activity that forces the arithmetic, or forces a wage decision against a rising cost of labor, makes that rule stick.

1. The hiring simulation, 20 minutes

Every student firm gets the same setup: an output price of $5 per unit and a marginal product schedule for six candidate workers, 14, 12, 10, 8, 6, and 4 units for the first through sixth. First task: compute marginal revenue product for each, MP times price. The answers are $70, $60, $50, $40, $30, and $20.

Run three rounds at three wages, requiring a hire or stop decision before each worker. At $45 per day, worker three's $50 clears the bar and worker four's $40 does not, stop at three. At $35, worker four's $40 clears it, stop at four. At $25, worker five's $30 clears it, stop at five. Students check each comparison by hand, then use the marginal revenue product calculator to settle a contested row.

The debrief question: at a wage of $35, the firm hired a fourth worker worth exactly $40 but stopped before a fifth worth $30. Why stop instead of continuing until the extra output from one more worker hits zero?

The misconception it exposes: that firms hire until marginal product reaches zero. Marginal product falls from the first worker in most setups, so waiting for zero means paying several workers more than they are worth.

2. The one-employer town, 20 minutes

One student plays the only employer in a small town, a monopsony buyer of labor. A wage schedule sets what the firm must pay to attract a given number of workers, and that wage goes to everyone already hired, not only the new hire: $10 for one worker, $12 for two, $14 for three, $16 for four, $18 for five.

Students find total labor cost at each level, then the marginal resource cost of one more worker: worker two raises cost from $10 to $24, MRC $14. Worker three, $24 to $42, MRC $18. Worker four, $42 to $64, MRC $22. Worker five, $64 to $90, MRC $26.

Give the firm a marginal revenue product for each candidate: $24, $20, $18, $14, $10. It hires while MRP is at least MRC: worker one clears $10, worker two clears $14, worker three clears $18 exactly, worker four's $14 does not clear $22. The town hires three, paying all three the wage needed to attract the third, $14, though that worker generates $18.

The debrief question: the third worker produces $18 in revenue and is paid $14. Where did the other $4 go?

The misconception it exposes: that the added cost of hiring one more worker is just that worker's wage. With a single buyer, hiring one more means raising pay for everyone already on the payroll, which is why marginal resource cost sits above supply instead of on it, the mechanism behind monopsony explained.

3. The derived-demand relay, 15 minutes

Four stations, four students per group, and a shock that starts in the product market: demand for a firm's output triples. For a leftover group of two, one student runs stations one and two and the other runs three and four. Station one converts that into a change in the output price. Station two multiplies the new price by the unchanged marginal product schedule for the new marginal revenue product. Station three draws the shift in labor demand. Station four reads off the new wage and quantity hired.

Each station sees only the prior station's written answer, never the original prompt, so one wrong answer breaks every station after it.

The debrief question: which station is most likely to break the chain, and what is the full path from the product market to the paycheck?

The misconception it exposes: that wages move for reasons internal to the labor market alone, when most wage changes trace back to a shock in the market for whatever labor is producing.

4. Predict then reveal, 5 minutes

Put two labor markets on the board, one competitive with a horizontal supply curve, one monopsony with an upward-sloping one. Announce the same minimum wage for both. Before revealing anything, students privately predict what happens to employment in each: rises, falls, or stays the same.

Reveal both. In the competitive market the wage floor sits above equilibrium and a labor surplus appears, employment falls. In the monopsony market, a floor set between the monopsony wage and the point where supply meets marginal revenue product raises the wage and raises employment at once.

The debrief question: which prediction surprised you, and why does the same policy produce opposite employment effects on the two graphs?

The misconception it exposes: that a minimum wage always cuts employment. That is correct under competition and wrong under monopsony within a specific range, and a class that only sees the competitive graph never learns the range exists.

5. The minimum wage debate, 20 minutes

Two teams argue opposite conclusions about the same policy, but neither may open with a conclusion. Each must first state, out loud, which market structure its argument assumes.

Team competitive argues a wage floor above equilibrium leaves willing workers unable to find hours, using the horizontal-supply graph to show the gap. Team monopsony argues a floor set near the competitive wage can raise both the wage and employment, using the upward-sloping-supply graph to show why. Source for either side: minimum wage economics.

The debrief question: a rural hospital that is the only employer of nurses in the county, versus a national fast food chain hiring in a large city, which structure fits which, and does the conclusion change?

The misconception it exposes: that minimum wage has one universal effect, when the honest answer depends on an assumption most arguments never state.

6. The least-cost input lab, 15 minutes

A firm is choosing between one more worker and one more machine. An added worker has a marginal product of 40 units and costs $20 an hour, so marginal product per dollar is 40 divided by 20, 2 units per dollar. An added machine has a marginal product of 60 units and costs $20 to rent, so its marginal product per dollar is 60 divided by 20, 3 units per dollar.

Since capital's ratio, 3, exceeds labor's, 2, the firm is not minimizing cost at its current mix. Students reallocate toward capital, recomputing both ratios as diminishing returns set in, stopping only when the two are equal.

The debrief question: the machine has the higher marginal product per dollar. Should the firm buy only machines and no labor? Why does the rule call for reallocating at the margin instead of switching entirely to one input?

The misconception it exposes: that the least-cost rule means picking the input with the higher marginal product, or the cheaper input, rather than equalizing marginal product per dollar across every input in use.

7. Sandbox closer, 10 minutes

Open the factor markets sandbox, hand the controls to one student, and let the class direct the moves. Drag the labor demand curve, labeled DL = MRP, right to represent a rise in output price. Then set the wage level control above the new equilibrium as a minimum wage would, and read off labor demanded against labor supplied at that wage.

The debrief question: which number changed because of the shift in the product market, and which because of the wage floor?

The misconception it exposes: that a shift in a curve and a movement along a curve are the same kind of change.

Sequencing

A workable arc across a factor markets unit: predict then reveal to surface existing beliefs about minimum wage, the hiring simulation to install the MRP equals wage rule with real arithmetic, the derived-demand relay to connect the product market to the paycheck, the least-cost lab to add a second input, the one-employer town to break the assumption that every firm is a wage taker, the minimum wage debate to force market structure into the open, and the sandbox to close with the same graph the unit was built around.

Full timings, objectives, and exit tickets for a factor markets unit are in the lesson plans library, and the model behind every activity above is taught in the factor markets module.