Lesson 6: The MTBH and the Design Envelope, Instructor Session Plan

This is where the program gets specific. The customer gave the student data; now the student has to decide what that data means for the design. The one outcome every student must leave with: a min and a max aren't design inputs until you know the volume behind each. If they walk out ready to size a conveyor from a spreadsheet's two extremes, the lesson didn't land. Keep them off the calculator today. The calculator is Lesson 7. Today is the reading that tells the calculator what to chew on.

Run of Show (60-minute baseline)

Segment	Min	What happens
Open on the min-max trap	6	Read the min-max trap hook aloud, then put one real over-engineered system on the board from your own work, a conveyor sized to an edge case almost nobody shipped. Land the frame: the min and max on a spreadsheet are often two percent of volume driving a hundred percent of the design. Tell the story, don't lecture it.
The six data points	10	Walk the six: length, width, height, weight, packaging type, volume distribution. Spend the time on the last two. Ask which two they'd have skipped, then show why volume distribution is the column that turns a min and a max into design inputs. Name the MTBH table as a deliverable they carry the rest of the program.
Min, max, average on the board	12	Three columns on the whiteboard. Under each, write what it drives: minimum is roller centers and gap, maximum is belt width and curve geometry, average is speed and throughput. Make the room give you a specific engineering decision under each before you fill it in. This is the heart of the reading.
The outlier conversation	14	Key teaching moment, below. Present a data set with an obvious outlier and run the two-version analysis live so the room watches the conveyor width jump when the outlier goes in. Land the move: show the customer both versions and let them decide.
The envelope as a contract	8	Define it: inside is automatic, outside is a defined exception path, agreed with the customer, documented, revisited when the mix changes. Land the design principle, a system designed to handle everything can be blamed for anything. Stress the sign-off. Silent envelopes are the failure mode.
Riverside build and close	10	Riverside facilitation, below. Students build the Riverside MTBH table and defend the two outlier candidates. Run the Tall Case debate. Close by tracing the table forward: this exact data is what Lesson 7 walks. Fold the forest close in here if you're tight.
Total	60	Baseline session. Expand with the stretch options below if you have 90 minutes.

Stretch options (for a 90-minute block):

Find the hidden outlier (add 15 min): hand the room a second product mix with an outlier buried in it and no volume flags. Have them find it and say what it would cost the design. Repetition against a fresh mix is what turns the volume question into a reflex.
Argue the full range (add 10 min): have a student make the case for designing straight to the customer's full min-to-max range, then have the room take it apart. Arguing the wrong answer out loud exposes whether they understand the right one.
Write the envelope (add 10 min): have students draft the actual envelope statement and the sign-off language they'd put in front of Dana. Making them write it down is how the abstract idea becomes a real artifact.

KEY TEACHING MOMENT | THE LIVE OUTLIER DEMO

Present a product data set with an obvious outlier, something four times the size of everything else at two percent of volume. Ask the room three questions and let them sit: do you design the whole system around this? What does it cost? What's the alternative?

Then run it live. Load the analysis with the outlier in and show the conveyor width the mix demands. Pull the outlier out and run it again. Let them watch the width drop. That jump on the screen is the cost driver made visible, and it's the seed of the cost-driver conversation they'll run for real in the proposal. Don't hand them the answer. The point is that the exclusion is a customer decision. The engineer's job is to price both versions and put them side by side.

WATCH-FORS

The failure this lesson exists to prevent is an engineer who takes the spreadsheet at face value. Watch for it and drive them back to the volume question every time. Signs:

They design straight to the customer's min and max without asking what percent of volume each end represents. Send them back to the volume column.
They produce an MTBH table with no volume-distribution column. It isn't an MTBH table yet. Make them add it.
They set the design envelope silently, in their own head, and never write it down or take it to the customer. Name it: an envelope nobody agreed to isn't scope control, it's a liability.
They reach for the calculator before the analysis. The analysis comes first. The calculator is Lesson 7.

RIVERSIDE FACILITATION | THE OUTLIER DEFENSE

Have students build the Riverside MTBH table from the four-product WMS report, then defend which two products they'd flag as outlier candidates. The answer you're steering toward is the two thin tails: the Small Case at 4 percent and the Large Case at 6 percent. Both sit under the five percent line where a product becomes a candidate for manual handling instead of a design driver.

Expect a fight about the Tall Case. It's the awkward one, tall on a narrow base, but at 12 percent of volume it's well above any exclusion threshold, so it stays inside the envelope and gets flagged for the decline instead. Don't settle any of it for them. Grade the reasoning, not the label. And make one thing explicit: the recommendation goes to the customer. The engineer doesn't make the exclusion call alone. A student who quietly drops the Large Case because it's inconvenient has missed the lesson as badly as one who keeps everything.

INSTRUCTOR ONLY | DO NOT SHARE WITH STUDENTS

Keep the project-note habit alive from Part I. The MTBH table the students build this session isn't just a lesson exercise. It's one of the artifacts a disciplined student arrives at the capstone already holding, built, dated, and filed in the Riverside note they've kept since Lesson 1. The ones who treat it as a real deliverable now walk into the capstone with the product analysis already in hand.

Don't tell them that. Never point at the payoff. Just keep framing the MTBH table as what a professional produces and keeps. The habit lands hardest on the students who built it without being told why it mattered.