DSE Economics | Opportunity Cost and the PPC Lesson-Prep Guide (Tutor Edition)

DSE Economics | Opportunity Cost and the PPC Lesson-Prep Guide (Tutor Edition) | Trade-offs, Increasing Cost and Growth

2026-11-03

Tutor lesson-prep guides · Secondary Economics

Students can recite “the highest-valued forgone option” yet answer “zero” the moment they see the word free. This lesson rebuilds free with two ledgers, money and time.

Objectives — Students can: (1) judge opportunity cost by the highest-valued forgone option, including non-money costs; (2) read trade-off, increasing cost and unemployed points off a PPC; (3) name the three sources of an outward shift and separate a movement along the curve from a shift.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Trade-off	What do we call limited resources against unlimited wants?	Scarcity
Money cost	Is a tuition fee part of opportunity cost?	Yes, but only part of it
Reading graphs	What does a point on the curve mean?	A combination with full employment of resources

02 Lesson flow (60 minutes)

Time	Stage	Tutor does	Student does
0–10 min	Definition	Highest-valued forgone option	Give three everyday examples
10–24 min	Calculation	Time cost plus money cost	Work one example fully
24–38 min	The curve	Shape, slope and opportunity cost	Read increasing cost off the curve
38–48 min	Shifts	Along the curve versus outward shift	Classify five scenarios
48–56 min	Answer frame	Definition, explanation, conclusion	Rewrite one answer
56–60 min	Exit check	Three questions collected	Independent

03 Teaching script (read it out)

Scene 1: Opportunity cost always includes time

Example: a student can either take tuition or work part-time at $75 an hour for 8 hours a day. Choosing tuition forgoes 75 x 8 = $600 of income.
Add the tuition fee and travel time. Opportunity cost is the value of everything given up, not just notes and coins.
Make them answer: what is the opportunity cost of a free exhibition (the value of the queuing time).

Tutor move: use the student own timetable and price the hours given up.

Scene 2: The PPC: the slope is the opportunity cost

Producing 20 more units of X costs 60 units of Y, so each unit of X costs 60 / 20 = 3 units of Y.
A curve bowed outward means increasing opportunity cost, because resources are not perfectly transferable. A point inside means unemployment or waste; on the curve means full employment; outside is currently impossible.

Tutor move: make them point at two dots and say what is given up.

Scene 3: Shifts: growth is not a move along the line

Three sources of an outward shift: more resources, better resource quality (technology), and trade.
Test: moving from one point to another on the same curve is a trade-off; moving the whole curve out is a rise in capacity.
Warning: a gain in the ability to produce only one good shifts only one end of the curve, not the whole line in parallel.

Tutor move: five scenario cards, two piles only: along or outward.

04 Question types and worked steps

Type	Example	Steps	Answer
Definition	Judge the opportunity cost of a choice	List forgone options, take the highest value	Money alone is wrong
Calculation	Convert time into income	Wage times hours	$600
Graph	Read opportunity cost from the slope	Fall in Y divided by rise in X	3 units of Y
Classify	Movement along or shift out	Ask whether capacity changed	A shift needs one of three sources

Sanity check (teach this): Opportunity cost is always what is given up; a sunk cost already paid is not part of it. Every point on the curve has a different cost, higher towards the ends. Always state units: 3 units of Y is not 3.

05 Independent practice (3 questions)

Question	Answer	What to watch
Wage $75 for 8 hours, income forgone	$600	Wage times hours
20 more X costs 60 Y, cost per unit of X	3 units of Y	Y divided by X
What does a point inside the curve show	Unemployment or unused resources	Not impossible, just unused

06 Common mistakes and what to say

Mistake	Student writes	Say this
Free means zero cost	Answers that opportunity cost is zero	“Only the price is zero; time and queuing are costs.”
Money only	Omits forgone income	“Your time has a market price; leave it out and the answer shrinks.”
Shift for a movement	Calls a demand rise an outward shift	“Capacity did not change, so it is a move along the curve.”
Slope inverted	Divides X by Y	“X is horizontal, Y is vertical; cost is vertical over horizontal.”

07 Homework (paper, section and question numbers)

Opportunity cost worksheet (in-house) — Questions 1–3: cost three choices
PPC reading worksheet (in-house) — Questions 4–6: classify five scenarios and draw a shift

08 Exit check (last 5 minutes)

Question	Answer	Decision
Opportunity cost of 8 hours at $75	$600	Missing time cost: reteach the definition
20 more X for 60 Y, cost per unit	3 units of Y	Inverted: re-drill the slope
New production technology, what happens to the curve	It shifts outward as a whole	All correct: move to demand and supply

09 Tutor FAQ

Does sleep have an opportunity cost?

Yes: the value of whatever else could have been done.

Is the curve always bowed outward?

It is a straight line when resources are perfectly transferable.

Is unemployment a cost?

It is unused capacity inside the curve, not an opportunity cost.

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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.