DESIGN · GRADES 9-12, CTE, UNIVERSITY · 20 MINUTES
The MacLeamy Curve: Decision Timing in Design lesson plan
Students predict, tour and redraw the four-line chart architects use to argue for deciding early, then name the next commitment on a real project and the decision to check before it.
On this page: Teach it in 5 steps · Student card · Printable
At a glance
Time: 20 minutes
Grades: Grades 9-12, CTE, University
Subject: Design: Decision Timing in Design
Grouping: Whole class, then individual
Space: Any classroom with a projector; the optional floor extension needs a 10 ft by 12 ft clear area
Teacher prep: 5 min printing
Included: Teacher script for every tour step, student sheet, checks for understanding, exit ticket with answers
Open the printable lesson: teacher script, student sheet and answer key (PDF) →
Teach it in 5 steps
The whole lesson on one screen. Details for each step are further down.
Before class (5 min): Print the student sheet and have the lesson page ready to project.
Hook (0-2 min): Project the page. "A family wants a bigger kitchen island. When is the cheapest moment to change it?"
Predict (2-4 min): Students draw their guess of line 2, the cost of a change, in Box A and circle how sure they are.
Main work (4-17 min): Work through items 3-10 of the procedure below, pausing on each question.
Check (17-20 min): Exit ticket: Name one commitment on a building project that makes a change harder to undo.
Student card
Read this part with your class, or print it for each team.
Your challenge
A family wants a bigger kitchen island. Work out when changing it is cheap, when it gets expensive, and what to check before it is too late.
By the end, I can:
read the four lines of the MacLeamy Curve and say what each one shows
explain why a change usually costs more later in a project
name the next commitment on a project and one decision to check before it
Who uses this
architects, project managers, construction estimators and owners planning a building, who decide what to check before drawings are issued, orders are placed or concrete is poured.
Essential question
When is the best time to change your mind on a building project, and how do you know?
What students learn and show
The big idea: the MacLeamy Curve is a model of decision timing with four lines and no scale: power to shape the result falls, the cost of a change rises, and the preferred process moves design work earlier.
Show it: a prediction and a from-memory sketch of the cost-of-change line, a one-sentence explanation, four quiz answers and an exit ticket that ties one decision to the commitment it must come before.
Objectives
Students identify what each of the four lines measures.
Students explain, in one sentence, why the cost of a change rises over a project.
Students explain why the crossing point is not a deadline (the chart has no scale).
Students plan one decision check before a named commitment.
Materials and prep
The interactive chart at bigfloorplans.com/macleamy-curve, projected (free, no login)
The two-page student worksheet from the printable, one per student
Optional floor extension: painter's tape and a tape measure, or a 1:1 printed kitchen plan
Lesson procedure
Teacher model: run the page's "Take the tour" on the projector, one step at a time, pausing at the questions below. Students commit to a prediction before line 2 appears.
0-2 min, Hook: Project the page. "A family wants a bigger kitchen island. When is the cheapest moment to change it?" Ask: Hands up: while it is a sketch, after the drawings, after the cabinets are ordered, or after they are installed? Listen for: Most say "while it is a sketch". Do not confirm yet.
2-4 min, Predict (tour step 3, first part): Students draw their guess of line 2, the cost of a change, in Box A and circle how sure they are. Silent, 90 seconds. Ask: What shape did you draw, and how sure are you? Listen for: Any shape is fine. The point is to commit before seeing it.
4-5 min, Step 1: time runs left to right: Start the tour. Point at the strip of seven stages along the bottom. Ask: Which stages are still only on paper? Listen for: PD, SD, DD and CD: the first four.
5-6 min, Step 2: line 1, power to shape the result: Reveal line 1. Ask: Why does this line only ever fall? Listen for: Each decision closes a few doors; nothing re-opens them.
6-8 min, Step 3: line 2, cost of a change: Reveal line 2. Students compare it with Box A, then write one sentence in Box B: why would a change cost more late? Ask: Who was close? What did you miss? Listen for: Early, a change is mostly design work; later it means re-approving, re-ordering or tearing out finished work.
8-10 min, Step 4: where lines 1 and 2 cross: Drag the slider to draw one line smaller. Watch the crossing move. Ask: If the crossing moves when we redraw a line, is it a deadline? Listen for: No. The chart has no scale, so the crossing is an accident of the drawing.
10-11 min, Step 5: line 3, traditional design work: Reveal line 3. Ask: Where does most of the design work happen? Listen for: Inside construction documents, where changes already cost more.
11-12 min, Step 6: line 4, preferred design work: Reveal line 4. Optional: open "Move the design work earlier" and drag the slider from 27% to 82%. Ask: What does line 4 change: how much design work, or when? Listen for: When. CURT calls it "a new distribution of design effort".
12-14 min, Step 7: recall: Hide line 2 (Test yourself). Students draw it from memory in Box C, without looking. Ask: Compare Box C with Box A. What changed in your thinking? Listen for: Line 2 gets steeper and never levels off.
14-17 min, Check yourself: Run the four quiz questions on the page. Students answer on the sheet first, then click to reveal. Ask: Which question split the room? Listen for: Q2 (the 100 times claim) usually splits it.
17-20 min, Exit ticket: Students complete the exit ticket. Collect.
Checks for understanding
Ask: Why does line 1 only fall? Look for: Each decision closes options; none re-open.
Ask: What does line 2 measure, and what doesn't it tell you? Look for: The cost of a change over time; not how much, because there is no scale.
Ask: What is the difference between line 3 and line 4? Look for: When the design work happens, not how much of it.
Exit ticket
Name one commitment on a building project that makes a change harder to undo. Answer: Any real commitment: signing off the layout, issuing permit drawings, placing an order, pouring a slab.
Name one decision you would check before that commitment, and how you would check it. Answer: A specific decision tied to that commitment, checked before it (e.g. island size before the cabinet order, by walking it at full size).
True or false: the point where lines 1 and 2 cross is a deadline. Explain in one sentence. Answer: False. The chart has no scale; draw either line smaller and the crossing moves.
Scoring: 3 of 3 with a specific commitment, a decision tied to it, and "false" with the no-scale reason = secure.
Common misconceptions
Students may think: The chart proves late changes cost 10 or 100 times more. Address it: Neither axis has numbers. Point at the axes and ask what the units are.
Students may think: Early changes are free. Address it: They cost less, not nothing: design, engineering and approval time still count.
Students may think: The crossing point is a deadline. Address it: Drag the step 4 slider: the crossing moves when one line is redrawn.
Supports and extensions
Learning support: give the four line names as cards; students match each card to a line before step 3.
Multilingual learners: pre-teach commitment, order, permit and procurement with the stage strip; allow the written answer in any language.
On the floor (optional, +15 minutes): tape out a kitchen island at full size (for example 3 ft by 6 ft) with a 42 in aisle on one side and a 36 in aisle on the other, or roll out a 1:1 printed kitchen plan. Two students pass each other with the dishwasher door open. Then announce that the cabinets are ordered next Monday: teams decide whether to change the island now and say what a change after the order would disturb.
Transfer task: pick a real project at school, such as a new lab or a gym floor, and list its next three commitments and one decision to check before each.
Ready to teach it?
The printable has the teacher script, the student worksheet and the answer key. Open the printable lesson →
Need the floor plan itself? Get a 1:1 print quote.
Paying for the print? Use a grant
Many teachers fund the 1:1 print with Toshiba America Foundation grants (grades 6-12) or your district's Title IV-A funds. Start from Renovate the Teaching House: a high-school design project with real constraints, our grades 9-12 grant packet, and add this lesson to its timetable. The packet has a project description, measurable objectives, a lesson timetable, an evaluation plan, a budget and a principal letter, written to the questions funders ask.
Download the grant packet (PDF) · Editable Word version · All funding options
Standards connections
NGSS HS-ETS1-3: evaluate a solution against prioritized criteria and trade-offs
CCSS ELA RST.9-10.7: translate information shown in a chart into words, and back
Perkins V (CTE: Architecture & Construction): design and preconstruction career pathway practice
Connections show which skills the activity practices. They are not a claim of full coverage.
Why this approach
Predicting before seeing an answer improves learning, especially when the result surprises students. Limit: Lab studies with children and adults on numerical facts, not chart reading.
Recalling material from memory (here, redrawing line 2) strengthens long-term retention more than restudying it. Limit: College students and prose passages; effect sizes in classrooms vary.
About the chart: The MacLeamy Curve, explained traces the 2004 CURT white paper and checks the claims usually made about it.
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