Five teenagers take a road trip on a long weekend to spend time at a cabin in the woods, only to stumble upon creepy and mysterious objects in the basement. Reading Latin found in an old diary, they unwittingly reanimate a family of pain-worshipping zombies, who immediately begin to assault and kill the teens one by one. Marty, one of the teens, escapes death and leads the only other survivor, Dana, into a hidden underground complex he has found. There they learn that their road trip experience has been engineered behind the scenes—and that they have been constantly and subtly manipulated—by an unnamed organization that annually perform this rite, causing archetypal victims to suffer and act as sacrifices that keep ancient evil beings, called the Old Ones, asleep. By releasing containment mechanisms that cage nightmarish monsters, Dana and Marty create gory chaos, allowing them to make their way to the heart of the complex, where they must choose to die for the world, or with it.
Looking for fan theories for The Cabin in the Woods:
When Sitterson and Hadley are desperately waiting to see if Jules will take off her shirt, Truman the security guard says, “Does it really matter if…?” Hadley interrupts him to to say, “We’re not the only ones watching, kid.” Sitterson adds, “Got to keep the customers satisfied,” before turning to look at Truman and confirm, “You understand what’s a stake here?”
My question is: Who do you think the (diegetic) “other ones” watching are? Is it other control rooms? Why would they care? Is the Old Ones? Really? They have TVs in their sleeping chambers? Who else might it be?
The key system in The Cabin in the Woods is a public service, and all technological components can be understood as part of this service. It is, of course, not a typical consumer service for several reasons. Like the CIA, FBI, and CDC, the people who most benefit from this service—humanity at large—are aware of it barely, if at all. These protective services only work by forestalling a negative event like a terrorist action or plague. Unlike these real-world threats, if Control fails in their duties, there is no crisis management as a next step. There’s only the world ending. Additionally, it is not typical in that it is an ancient service that has built itself up over ages around a mystical core.
So who are the users of the service? The victims are not. They are intentionally kept in the dark, and it is seen as a crisis when Marty learns the truth.
Given that interaction design requires awareness of the service in question, as well as inputs and outputs to steer variables towards a goal, it stands that the organization in the complex are the primary users. Even more particularly it is Sitterson and Hadley, the two “stage managers” in charge of the control room for the event, who are the real users. Understanding their goals we can begin an analysis. Fittingly, it’s complex:
Forestall the end of the world…
by causing the (non-Virgin) victims to suffer and die before Dana (who represents the Virgin archetype)…
at the hand of a Horrible Monster selected by the victims themselves…
marking each successful sacrifice with a blood ritual…
while keeping the victims unaware of the behind-the-scenes truth.
Sitterson and Hadley dance in the control room.
Part of a larger network with similar goals
This operation is not the only one operating at the same time. There are at least six other operations, working with their particular archetypes and rituals around the world: Berlin, Kyoto, Rangoon, Stockholm, Buenos Aires, and Madrid.
To monitor these other scenarios, there are two banks of CRT monitors high up on the back wall, each monitor dedicated to a different scenario. Notably, these are out of the stage manager’s line of attention when their focus is on their own.
The CRT monitors display other scenarios around the world.
The digital screens on the main console are much more malleable, however, and can be switched to display any of the analog video feeds if any special attention needs to be paid to it.
The amount of information that the stage managers need about any particular scenario is simple: What’s the current state of an ongoing scenario, and whether it has succeeded or failed for a concluded one. We don’t see any scenario succeed in this movie, so we can’t evaluate that output signal. Instead, they all fail. When they fail, a final image is displayed on the CRT with a blinking red legend “FAIL” superimposed across it, so it’s clear when you look at the screen (and catch it in the “on” part of the blink) what it’s status is.
Sitterson watches the Kyoto scenario fail.
Hadley sees that other scenarios have all failed.
One critique of this simple pass-fail signal is that it is an important signal that might be entirely missed, if the stage managers’ attentions were riveted forward, to problems in their own scenario. Another design option would be to alert Sitterson and Hadley to the moment of change with a signal in their peripheral attention, like a flash or a brief buzz. But signaling a change of state might not be enough. The new state, i.e. 4 of 7 failed, ought to be persistent in their field of vision as they continue their work, if the signal is considered an important motivator.
The design of alternate, persistent signals depend on rules we do not have access to. Are more successful scenarios somehow better? Or is it a simple OR-chain, with just one success meaning success overall? Presuming it’s the latter, strips of lighting around the big screens could become increasingly bright red, for instance, or a seven-sided figure mounted around the control room could have wedges turn red when those scenarios failed. Such environmental signals would allow the information to be glanceable, and remind the stage managers of the increasing importance of their own scenario. These signals could turn green at the first success as well, letting them know that the pressure is off and that what remains of their own scenario is to be run as a drill.
There is a Prisoner’s Dilemma argument to be made that stage managers should not have the information about the other scenarios at all, in order to keep each operation running at peak efficiency, but this would not have served the narrative as well.
The mission is world-critical, so like a cockpit, the two who are ultimately in control are kept secure. The control room is accessible (to mere humans, anyway) only through a vault door with an armed guard. Hadley and Sitterson must present IDs to the guard before he grants them access.
Sitterson and Hadley pass security.
Truman, the guard, takes and swipes their cards through a groove in a hand-held device. We are not shown what is on the tiny screen, but we do hear the device’s quick chirps to confirm the positive identity. That sound means that Truman’s eyes aren’t tied to the screen. He can listen for confirmation and monitor the people in front of him for any sign of nervousness or subterfuge.
Hadley boots up the control room screens.
The room itself tells a rich story through its interfaces alone. The wooden panels at the back access Bronze Age technology with its wooden-handled gears, glass bowls, and mechanical devices that smash vials of blood. The massive panel at which they sit is full of Space Age pushbuttons, rheostats, and levers. On the walls behind them are banks of CRT screens. These are augmented with Digital Age, massive, flat panel displays and touch panel screens within easy reach on the console. This is a system that has grown and evolved for eons, with layers of technology that add up to a tangled but functional means of surveillance and control.
The interfaces hint at the great age of the operation.
In order for Control to do their job, they have to keep tabs on the victims at all times, even long before the event: Are the sacrifices conforming to archetype? Do they have a reason to head to the cabin?
The nest empties.
To these ends, there are field agents in the world reporting back by earpiece, and everything about the cabin is wired for video and audio: The rooms, the surrounding woods, even the nearby lake.
Once the ritual sacrifice begins, they have to keep an even tighter surveillance: Are they behaving according to trope? Do they realize the dark truth? Is the Virgin suffering but safe? A lot of the technology seen in the control room is dedicated to this core function of monitoring.
The stage managers monitor the victims.
There are huge screens at the front of the room. There are manual controls for these screens on the big panel. There is an array of CRTs on the far right.
The small digital screens can display anything, but a mode we often see is a split in quarters, showing four cameras in the area of the stage. For example, all the cameras fixed on the rooms are on one screen. This provides a very useful peripheral signal in Sitterson and Hadley’s visual field. As they monitor the scenario, motion will catch their eyes. If that motion is not on a monitor they expect it to be, they can check what’s happening quickly by turning their head and fixating. This helps keep them tightly attuned to what’s happening in the different areas on “stage.”
For internal security, the entire complex is also wired for video, including the holding cages for the nightmare monsters.
Sitterson looks for the escapees amongst the cubes.
The control room watches the bloody chaos spread.
One screen that kind of confuses us appears to be biometrics of the victims. Are the victims implanted with devices for measuring such things, or are sophisticated non-invasive environmental sensors involved? Regardless of the mechanisms, if Control has access to vital signs, how are they mistaken about Marty’s death? We only get a short glance at the screen, so maybe it’s not vital signs, but simple, static biometrics like height, and weight, even though the radiograph diagram suggests more.
Sitterson tries to avoid talking to Mordecai.
Sitterson and Hadley are managing a huge production. It involves departments as broad ranging as chemistry, maintenance, and demolitions. To coordinate and troubleshoot during the ritual, two other communications options are available beyond the monitors; land phone lines and direct-connection, push-to-talk microphones.
We know in the film that Control has been working behind the scenes long before the event takes place. The Chem department, for example, has somehow gotten Jules to bleach her hair, and the hair dye “works its way into the blood” as a way to slow her cognition, and make her conform more the Whore archetype. Additionally, they have been lacing Marty’s marijuana to keep him dazed & confused. (Though, key to the plot, they missed his secret stash.) There’s even an actor placed en route to the eponymous cabin who unsettles the victims with his aggression and direct violent insults to Jules, setting the stage for their suffering. Though these things occur “off stage” of the actual cabin (and the Chem team works off screen), they help tell the story about how deeply embedded Control is in the world, and set the stage for the surveillance interfaces on stage.
Marking the deaths: on screen & ritually
The goal of the scenario is the suffering and death of the victims, in the right order. To provide a visual marker on the monitoring screens, a transparent red overlay is placed over victims who are believed to have been killed.
The choice of red has a natural association with the violence, but red has a number of problems. Visually, it vibrates against blue (according to opponent process of color theory, the red and blue receptors in our retinas are in the same place and can’t perceive both at the same time). It’s also typically used to grab attention, which in this case is the exact wrong signal. Jules is no longer in the picture, and so specifically no attention is needed for her. Better would be to dim her section on the monitor, or remove her altogether, if marking progress is unimportant.
Hadley orders Thorazine
In addition to marking the deaths in the digital interfaces, the deaths must be marked ritually for the system to work. To this end, Sitterson and Hadley act as the human interface that transfers the information from the electronic systems to the Bronze-Age mechanical systems behind him. Though this could be accomplished mechanically, there are ritual words that must be spoken and an amulet that must be kissed by a supplicant.
Sitterson, the senior of the two, recites, “This we offer in humility and fear / For the blessed peace of your eternal slumber / As it ever was.”
After these ritual actions, Hadley raises a roll top wooden panel to reveal a simple switch. Pulling it down initiates a chain of mechanics that ultimately break a vial of blood into a funnel, which channels the blood into grooves carved into a sacrificial slab.
Sitterson and Hadley mark the first sacrifice
The roll top door acts as a physical barrier against accidental activation, and the mechanical switch requires a manageable, but deliberate, amount of force. Both of these features in the interface ensure that it is only done when intended, and the careful mechanical construction ensures that it is done right.
The stage managers’ main raison d’être is to course-correct if and when victims begin to deviate from the path required of the ritual.
This begins with the Prep team, long before the victims enter the stage. For example, Jules’ hair dye and Marty’s laced pot. These corrections become more necessary and intense once the victims go on stage.
Making sure there are sexy times
The ritual requires that a sexy young couple have sexy times on stage before they suffer and die. “The mood” can be ruined by many things, but control has mechanisms to cope with most of them. We see three in the movie.
The temperature can’t be too hot or too cold, but this isn’t something that can be set and forgot. What counts as the right temperature is a subjective call for the people involved and their circumstances, such as being drunk, or amount and type of clothes worn. Fortunately, the video-audio panopticon lets the stage managers know when a victim speaks about this directly, and do something about it. The moment Jules complains, for instance, Sitterson is able to reach over to a touch-screen display and tap the temperature a few degrees warmer.
Sitterson heats things up.
The gauge is an interesting study. It implies a range possible between 48 and 92 degrees Fahrenheit, each of which is uncomfortable enough to encourage different behaviors in the victims, without the temperature itself being life-threatening.
Moreover, we see that it’s a “blind” control. Before Sitterson taps it, he is only shown the current temperature as a blue rectangle that fills up four bars and that it is exactly 64 degrees. But if he knew he wanted it to be 76 degrees, what, other than experience or training, tells him where he should touch to get to that desired new temperature? Though the gauge provides immediate feedback, it still places a burden on his long-term memory. And for novice users, such unlabeled controls require a trial-and-error method that isn’t ideal. Even the slim area of white coloring at the top, which helpfully indicates temperatures warmer than cooler, appears too late to be useful.
Better would be to have the color alongside or under the gauge with smaller numbers indicated along its length such that Sitterson could identify and target the right temperature on the first try.
The next thing that can risk the mood is a lack of a victim’s amorous feelings. Should someone not be “feeling it,” Control can pipe sex pheromones to areas on stage. We see Hadley doing this by operating a throttle lever on the electronic-era control panel. After Hadley raises this lever, we see small plumes of mist erupt from the mossy forest floor that Jules and Curt are walking across.
Hadley introduces pheromones to the forest air.
This control, too, is questionable. Let’s first presume it’s not a direct control, like a light switch, but more of a set-point control, like a thermostat. Similar to the temperature gauge above, this control misses some vital information for Hadley to know where to set the lever to have the desired amount of pheromone in the air, like a parts-per-million labeling along the side. Perhaps this readout occurs on a 7-segment readout nearby or a digital reading on some other screen, but we don’t see it.
There is also no indication about how Hadley has specified the location for the pheromone release. It’s unlikely that he’s releasing this everywhere on stage, lest this become a different sort of ritual altogether. There must be some way for him to indicate where, but we don’t see it in use. Perhaps it is one of the lit square buttons to his right.
An interesting question is why the temperature gauge and pheromone controls, which are similar set-point systems, use not just different mechanisms, but mechanisms from different eras. Certainly such differentiation would help the stage managers’ avoid mistaking one for the other, and inadvertently turn a cold room into an orgy, so perhaps it is a deliberate attempt to avoid this kind of mistake.
The final variable that stands in the way of Jules’ receptiveness (the authors here must acknowledge their own discomfort in having to write about this mechanistic rape in our standard detached and observational tone) is the level of light. After she complains that it is too dark, Hadley turns a simple potentiometer and the “moonlight” on a soft bed of moss behind them grows brighter.
Control responds to Jules’ objection to the darkness.
This, too, is a different control than the others; though it controls what is essentially a floating-point variable. But since it is more of a direct control than the other two, its design as a hard-stop dial makes sense, and keeps it nicely differentiated from the others.
Marty’s Subliminal Messages
Over the course of the movie, several times we hear subliminal messages spoken to directly control Marty. We never see the inputs used by Control, but they do, at least on one occasion, actually influence him, and is one of the ways the victims are nudged into place.
Marty breaks the fourth wall
In addition to Dana & Curt’s almost not getting it on, another control-room panic moment comes when Marty accidentally breaks a lamp and finds one of the tiny spy cameras embedded throughout the cabin. Knowing that this level of awareness or suspicion could seriously jeopardize the scenario, Hadley bolts to a microphone where he says, “Chem department, I need 500 ccs of Thorazine pumped into room 3!”
Marty finds a spy camera
Hadley speaks a command to the Chem department
Careful observers will note while watching the scene that a menu appears on a screen behind him as he’s stating this. The menu lists the following four drugs.
Cortisol (a stress hormone)
Pheromones (a category of hormonal social signals, most likely sex pheromones)
Thorazine (interestingly, an antipsychotic known to cause drowsiness and agitation)
Rhohyptase (aka Rhohypnol, the date rape drug)
Given that content, the timing of the menu is curious. It appears, overlaid on the victim monitoring screen, the moment that Hadley says “500.” (Before he can even specify “Thorazine.”) How does it appear so quickly? Either there’s a team in the Chem department also monitoring the scene, and who had already been building a best-guess menu for what Hadley might want in the situation and they just happened to push it to Hadley’s screen at that moment; Or there’s an algorithmic voice- and goal-awareness system that can respond quickly to the phrase “500 ccs” and provide the top four most likely options. That last one is unlikely, since…
We don’t see evidence of it anywhere else in the movie
Hadley addresses the Chem department explicitly
We’d expect him to have his eyes on the display, ready to make a selection on its touch surface, if this was something that happened routinely
But, if we were designing the system today with integrated voice recognition capabilities, it’s what we’d do.
Curt suggests they stick together
After the attack begins on the cabin itself, Curt wisely tells the others, “Look, we’ve got to lock this place down…We’ll go room by room, barricade every window and every door. We’ve got to play it safe. No matter what happens, we have to stay together.” Turns out this is a little too wise for Hadley’s tastes. Sitterson presses two yellow, back-lit buttons on his control panel to open vents in the hallway, that emit a mist. As Curt passes by the vents and inhales, he pauses, turns to the others and says, “This isn’t right…This isn’t right, we should split up. We can cover more ground that way.”
Sitterson knocks some sense out of Curt.
This two-button control seems to indicate drug (single dose) and location, which is sensible. But if you are asking users to select from different variables, it’s a better idea to differentiate them by clustering and color, to avoid mistakes and enable faster targeting.
Locking the doors
Once the victims are in their rooms, Hadley acknowledges it’s time to, “Lock ‘em in.” Sitterson flips a safety cover and presses a back-lit rocker switch, which emits a short beep and bolts the doors to all the victims’ rooms at the same time.
Sitterson bolts the victims’ doors.
Marty in particular notices the loud “clunk” as the bolts slide into place. He tests the door and is confounded when he finds it is, in fact, locked tight. Control’s earlier concern about tipping their hand seems to matter less and less, since this is a pretty obvious manipulation.
The edge of the world
Bolted doors pale in comparison to the moment when Curt, Dana, and Holden violently encounter the limits of the stage. After the demolition team seals the tunnel to prevent escape that way, Curt tries to jump the ravine to the other side so he can fetch help. Unfortunately for him, the ravine is actually an electrified display screen, showing a trompe-l’œil illusion of the far side. By trying to jump the ravine, Curt unwittingly commits suicide by slamming into it.
Curt slams into the edges of the “world” of the cabin.
The effect of the screen is spectacular, full of arcs zipping along hexagonal lines and sparks flying everywhere. Dana and Holden rush to the edge of the cliff to watch him tumble down its vast, concave surface. It seems that if you’ve come this far, Control isn’t as concerned about tipping its hand as it is finishing the job.
The breach is not well-handled by the systems around the control room. Not only do the lights not have a local backup power source, but the screens on the background display Big Labels saying unhelpful things like, “ESCAPE ALERT – UNKNOWN SECURITY BREACH.” If you were designing a system specifically to control nightmare monsters to sacrifice helpless victims, I think the first thing your risk officer should work out is a system that can recognize and withstand when one of those two things (monsters or victims) was out of place. The least you could do is provide users with extremely clear status messages about them.
Sitterson and Truman scan the video monitors for Dana and Marty.
After the breach, we see one more interface for the stage managers: an old escape route. Even though Control is world-critical, its designers imagined that things could go haywire. Presuming that other scenarios are going fine, if all hope is lost in this one, the stage managers have a way out of the control room. We only get a few glimpses of this interface, but it looks to be a computer-controlled security access lock whose 8-bit graphics imply that it was implemented in the early 1990s, around the time when Microsoft Windows 3.1 was the dominant computing paradigm.
Sitterson desperately enters his PID.
After working desperately a bit, Sitterson is able to get the system to a screen that asks for his PID. He uses a rubber-key keypad below the screen to enter it, and is told “SECURITY OVERRIDE GRANTED.” In this way he is able to open the trap door and escape the monsters swarming the control room.
Especially given the amount of stress that a user is likely to be under while using this interface, and the infrequency with which it must be used, it seems absolutely cruel to secure the door by a memorized identification number. Unless that PID is used frequently enough to become habit, it’s unlikely to be remembered when the user is trying to escape death. Better is to use the ID cards already seen in the film in combination with some biometric scan like retina or finger print.
There is a system in place to manage the “resources,” the nightmare creatures available to be chosen by the victims for their sacrifice. This management includes letting them out to the surface, putting them back in place safely, and containment throughout the intervening year between sacrifices.
Dana and Marty experience the cages from the perspective of a monster
The one interface element that we do see in use is the one that Dana and Marty use to release the imprisoned nightmare monsters throughout the complex. It is a single kill-switch button labeled “SYSTEM PURGE”, located on a panel in the security booth that overlooks the main elevator bank. While hiding from approaching security forces, Dana notices the switch beneath the monitoring screens. She flips a protective switch cover to enable it, sees a confirming amber light, and then slams down on the kill switch. Moments later, the first of several waves of nightmare monsters are released through the elevator doors into the complex.
Dana slams the System Purge kill switch.
From a story viewpoint, this is an awesome moment where the story becomes utter chaos and the workforce of jaded sacrificers get their horrible, horrible come-uppance. But from a design standpoint, it’s utter nonsense. Imagine a nuclear power plant where the kill switch, which is accessible through an unlocked door and labeled clearly for any saboteur to read, dumps live fuel rods and heavy water onto the heads of the plant operators. Or a zoo where the animals-are-furious-and-hungry switch dumps the animals right onto the grounds. A system like Control, with global reach and resources, would find some other space into which this murderous tsunami can be vented, and ensure proper security around the activation mechanism. Still, this makes for hilarious chaos and the “happy” ending, so as audience members we’re glad Control messed up on its design strategy.
Marty had already been shown to be able to hack Control’s electronics upstairs, so I suspect the narrative decision about the purge switch was made to give Dana some additional agency in this part of the story, and add some punch to the onset of the final act, so we’ll count that as a minor quibble, too.
There is another set of users of the Global Sacrifice System who bear a bit of consideration, and they are the Old Ones. They are users in the sense that this is an agreement into which they’ve entered with humanity, in order to get a continuing IV drip of (to them) pleasurable abject suffering and death. This isn’t an imposed frame on the story. The ritual spoken by Sitterson are not the words of a zookeeper managing a downed animal’s Ketamine. They’re the words of a supplicant.
As long as the organization keeps the sacrifices coming, providing the tasty intravenous drip of human suffering, the world is allowed to continue as it is for another year. With this in mind, we can analyze how the system works for those users, i.e. the Old Ones.
The outputs that the Old Ones read from the system are unavailable to us, but we can tell it’s kind of precise. There are allusions midway through the film that the titan below the cabin is somehow “watching” the sex scene. (Though that ambiguous line could refer to the ravenous horror-movie audience as well.) It can also somehow sense the suffering of the victims, and whether the details of the ritual are being carried out in the proper order. The way we know this is that when Marty’s “death” vial is inappropriately shattered, the titan causes an earthquake that rocks the complex and the cabin.
This, then, is the input that the Old Ones have: shaking the ground in their displeasure. But as a signal, it’s far too vague. Hadley and Sitterson feel the quake, but disregard it. Hadley shouts, “They must be getting excited downstairs!” and Sitterson replies somewhat jadedly, “Greatest show on earth.” Had they had any inkling that they had actually messed up (even absent of what precisely was messed up) they would have pulled out the stops to find the error and correct it.
So while we as an audience are all in favor of resetting of a world that has accepted annual ritual sacrifice of young people, neither party to the agreement—the Old Ones nor the humans—set in place a system of communication that is precise enough to keep the agreement going. And that’s a failing of the interface.
From the sudden and hilarious appearance of the title on screen, I knew that The Cabin in the Woods was going to be a special film. And in fact, it is one of my favorite movies of the past year, and dare I say one of the best sci-fi/horror hybrid movies of all time. (Admittedly it’s not a giant subgenre.) When we focus on the interfaces, they ultimately help tell this dark story of epic comeuppance, even if they stumble a bit on the details.
Sci: B+ (3 of 4) How believable are the interfaces given the science of the day?
The surveillance and control interfaces are all perfectly believable, even as they span different technological paradigms. There are some aspects of the interface that must be excused as “mystical,” and some toying with chemical science, i.e. human sex pheromones and the “let’s split up” chemical, that prevent us from awarding it full marks.
Fi: A (4 of 4)
How well do the interfaces inform the narrative of the story?
In addition to helping set the stage of a service that spans technological eras, nearly all of the problems help tell the story of a controlling organization that is only barely in control. It’s dysfunctional and jaded enough in the execution of its dark duty that we’re kind of OK with their failure and ultimate destruction. And much of the rest of the problems can be swept under the narrative rug of “it’s mystical,” again, in a very smart way. The only thing that takes us out of the narrative to ask “why” and “how” is the inexplicable cause-failure SYSTEM PURGE switch, but it ultimately just sped up a part of the film that could have been too slow in the wrong part.
Interfaces: C (2 of 4)
How well do the interfaces equip the characters to achieve their goals?
There’s lots of goodness in the interfaces to learn from: Solid clustering of monitoring signals, strong physical differentiation in the control dashboard, and even well-protected and well-labeled kill switches. But there are equally large problems as well: There are several blind controls that only permit expert use. There’s an escape hatch security system that only increases the panicked user’s panic. The communication system between the humans and Old Ones is ambiguous enough to cause world-class failures to communicate. For these reasons, you should be careful when pulling lessons for the real world from the interfaces found here.
Final Grade B+ (9 of 12), MUST-SEE
Related lessons from the book
The delightful mechanical controls in the film already embody the lesson Mix Mechanical and Other Controls Where Appropriate. (page 26)
Those same controls might have used some smarter grouping as seen in Chapter 3, Visual Interfaces. (page 55)
The control room interfaces should have remembered the lesson from the Communication Chapter, that Signaling Change of State isn’t Enough. (page 202)
The course-correction interfaces that nudged Jules and Curt into sex started to fulfill the Sex chapter’s Augment Everything opportunity. (page 301)
Suggested new lessons
The excellent differentiation seen in the control panel suggests a new lesson to Differentiate Physical Controls, such that they are easy to find by touch, and tell apart immediately.