Lesson 18: Control Philosophy, Instructor Session Plan

Lesson 18 opens Part V, the controls arc, and this is the depth part of the program. The one outcome every student must leave with is the five-layer topology in their head: drawn from memory, the right owner on each layer, and the instinct to ask which layer owns this before touching anything. Don't lecture the five names off a slide. Draw the stack on the board, keep it up the whole hour, and make the room narrate what moves between the layers. A student who can only recite the names has memorized without understanding, and this session exists to catch exactly that.

Run of Show (60-minute baseline)

Segment	Min	What happens
Open on the misdirected sort	6	Read the hook aloud. Put the driving question on the board and leave it up all session: which layer owns this decision? Three teams each swear the misdirects aren't theirs and the cartons keep going out the wrong door. Ask the room why it stays broken. Steer them to the answer: nobody has named the layer that owns it.
Build the topology live	14	Key teaching moment, below. Draw the five layers ground up against the rebranded diagram, owner named on each band. Then run the narration drill out loud. This is the center of the lesson. Do not shortchange it.
WCS vs WES	10	Draw the order-intelligence boundary. A WCS routes what the WMS tells it; a WES decides some order sequencing itself. Work the two concrete examples: divert carton 123 is a WCS decision either way, but batch-and-sequence forty orders is WES work if the execution layer owns it. Land it: ask what it decides, not what it's called.
The who-decides-what matrix	12	Class exercise. Call out a decision; the room calls back the owning layer and the owner. Release a wave, sequence a batch, divert a carton, stop a jammed zone, pick the carrier, format a read. Push back the moment they default to the PLC because the symptom sounds mechanical.
Riverside placement round-robin	12	Facilitation below. Hand out the blank stack and Ray's WMS quote. Each student places one component and defends it to the room. Steer them to discover the open item for themselves.
Forest and close	6	Tie it back to the driving question on the board. Every remaining Part V lesson is depth inside one of these five layers. Collect the topology placements before they leave.
Total	60	Baseline session. Expand with the stretch options below if you have a 90-minute block.

Stretch options (for a 90-minute block):

Place a real architecture (add 20 min): bring a real customer's system architecture, or the capstone's, and have students place it on the five layers piece by piece. Placing a second, messier system is what turns the stack from a diagram into a working tool.
Narrate it in reverse (add 5 min): run the drill downward. A divert just executed on the sorter. Walk me back up every layer to the wave that started it and the order behind the wave. The status path is as real as the instruction path.
Argue the spec (add 5 min): hand the room a quote that lists a WCS for an operation that needs order execution. Have one student defend the quote and the rest take it apart. Arguing it out loud exposes whether they can tell the two layers of responsibility apart.

KEY TEACHING MOMENT | DRAW THE STACK, THEN NARRATE IT

Go to the board and draw the five layers from the ground up: Machine Controls and the PLC at the bottom, then middleware, then WCS/WES, then the WMS, then the ERP on top. Keep it up for the whole hour and point at it every time a layer comes up. Name the owner on each band as you draw it, because the owner is half of what the diagram teaches.

Then run the drill, out loud, every time you teach this. The WMS sends a wave to the floor. A carton reaches the scan point. Walk me through every layer of the topology from that scan to the physical divert on the sorter. Make one student narrate the whole path and make the rest of the room catch what they skip. A student who can tell you what moves between the layers, the read going up, the routing coming back down, the confirmation after the divert fires, understands the architecture. A student who can only recite the five names has memorized without understanding. The narration is the test, not the recital.

WATCH-FORS

Three failure modes to catch and correct on the spot. Drive every one back to the ownership matrix: name the decision, then name the layer.

Students who can list the five names but can't say what moves between them. Put them on the narration drill until they can walk a carton up and back down the stack without you.
Students who default every problem to "it's the PLC" because the symptom is mechanical. A misdirect is just as often a bad read, a bad translation, or a wrong destination returned from three layers up. Make them locate the decision before they name the machine.
Students who treat WCS and WES as the same thing. Send them back to the boundary: a WES makes order-side decisions a WCS never touches, and speccing the wrong one leaves a whole layer of decisions with no owner.

RIVERSIDE FACILITATION | PLACE THE COMPONENTS, FIND THE OPEN ITEM

Hand out a blank five-layer stack and Ray's WMS description from the discovery meeting: "We run a standard WMS. It manages all picking, inventory, and order release. When an order wave goes out the WMS knows which carrier each carton is going to. That information is tied to the barcode on each carton." Have each student place a Riverside component on its layer and defend the placement: the EZLogic zones and the divert PLC at Layer 1, the middleware at Layer 2, the which-door decision at Layer 3, Ray's WMS at Layer 4, the ERP at Layer 5.

Then steer them toward the open item without handing it over. Ask what number on this architecture is still unconfirmed. Let them find that Ray's half-second WMS response time was flagged as a guess, and that it sits at the Layer 2/3 boundary where the routing query crosses. Do not tell them. Ask. A student who discovers the open item on their own will keep it in their note. One who is handed it will forget it by next session.

CHECKPOINT ANSWER KEY | NOT IN THE STUDENT FILE

Isolating the misdirect. A strong answer walks the stack instead of guessing the machine. At Layer 1: is the read good, and did the divert fire when commanded? At Layer 2: did the read get translated and passed up, and did a routing instruction come back down intact? At Layer 3: did the WCS return the correct destination for that barcode? At Layer 4: was the wave current, or is the WMS working from stale carrier-to-barcode data? The point isn't a single right layer. It's that a wrong-door symptom can originate at any of four layers, and the student isolates it by asking one clean question at each until the answers stop being clean. Sensing failure modes such as no-read and lost track live at Layer 1 and are named, not diagnosed, here; that depth is Lesson 19.
The WCS-versus-WES question. The question to ask: does the quoted system decide the order batching and pick sequencing itself, or does it only execute sequencing handed down to it from the WMS? If it decides, it's functioning as a WES and covers the need; if it only executes, it's a plain WCS and the order-side decisions have no owner in this quote. It changes what the customer is buying because a WCS that can't make order-side decisions leaves that whole layer of work on their aging WMS, which is the system they were trying to get out from under. Same word on the quote, two very different scopes of responsibility.

INSTRUCTOR ONLY | DO NOT SHARE WITH STUDENTS

Ray's unconfirmed half-second is a seed, not a loose end. It's the front of a thread that pays off later in Part V, when a correction arrives and the number the whole controls architecture was designed to turns out to be wrong. The students who kept the open item in their Riverside note, dated and findable, are the ones who will be ready when it comes back. The ones who waved it off will redo work.

Don't preview any of that. Your only job today is to make the open item feel like an ordinary part of documenting an architecture: you found an unconfirmed number, you flagged it, you kept it where you'd find it again. That documentation discipline is the real lesson hiding inside this one, and it lands hardest on the students who were never told why it mattered.