This is one of the homepages of the device. The counters (2, 4) reflect how many washers and dryers are available for use. Available for use can either mean that someone else's close are sitting in the machine and need to be moved to a dryer, or it can mean that the machine is empty. To continue, the user needs to press either the "Claim Washer" or "Claim Dryer" button. Note that the workflow for washers and dryers is split very early on in the process.
In our scenario, Ginny needs to wash her clothes, so she presses the "Claim Washer" button.
From this page, Ginny can see the names of the washers that are available, as well as select them by pressing the "Select" button. She can also press the "View on Map" button next to the name of each washer to see a map of the whole laundry space with the specific machine highlighted (this is not a feature that we have detailed in this scenario). Additionally, Ginny can view notes on each machine left by previous users. Ginny views the note on Washer 3.
When Ginny presses the "View Note" button, a popover appears with the text of the note. From here, she can choose to close the note, or message the other user a question. To leave the screen, Ginny can either hit the "Close Note" or "Send Message" buttons. Note that when the popover appears, the rest of the screen will be dimmed so that the "Back" and "Continue" buttons do not appear to be selectable.
Going back to the previous screen, Ginny presses the "Select" button for Washer 3 and Washer 5. This changes the color of the button, as well as changes the text of the button to read "Deselect". If Ginny presses the button again, the button will return to its original state. Ginny can also hit the "Back" button to return to the homepage, or "Continue" to proceed. Ginny presses "Continue".
Here, Ginny can see the washers she selected from the previous screen. The "Back" and "Continue" buttons remain at the bottom of the screen for consistency. Each washer image has a "Leave Note" button, which Ginny can press to leave a message for the person who moves her laundry to the dryer. Ginny does this for Washer 3. 
Again, a popover appears, where Ginny types in her message and presses "Leave Note" to finish the action. This closes the popover, and she presses the "Continue" button once more.
Ginny now reaches the end of the workflow. This screen intentionally looks very similar to the homepage, so that Ginny gets the feel that this is an entry/exit point to the app. Ginny sees how much time is left until her clothes will be done, and can press the "Notify Me" button to receive a text notification when her clothes are ready. She chooses to do this.
This is the version of the homepage that Ginny will see until her clothes are finished washing. It's nearly identical to the previous screen.
This is another version of the homepage that Ginny would have seen at the beginning of the workflow if there were no open washers or dryers.
Analysis
Learnability
This design features self consistency, well-known UI features such as buttons and popovers, and guided start-to-finish workflow. Because of this, we feel this design is very learnable. Perhaps the one place in the design lacking in learnability is in the exchange of messages between users. It is unclear to the user how he/she'd view a message sent from another user, or how he/she'd reply to such a message.
Use of timers and counts adds to the useful information presented immediately to the user, making this design clear and learnable.
Efficiency
This design has a few efficiency issues. First, using the workflow model, while great for learnability, can potentially slow down an experienced user. Adding some sort of bypass for experienced users might be beneficial. Second, since the washer and dryer workflows are separated very early on in the process, a user cannot select washers and dryers at the same time. A possible solution to this would be to move the split of the two further down the workflow, or remove it entirely; the consequences of this would be a more cluttered design and, in our opinion, a worse user experience.
Safety
There are a few safety issues in this design. When leaving a message for another user, there is no indication that the user can save the message for later use. Additionally, there's no clear way for the user to load a previously saved message. Additionally, the user is not forced to view the note of the previous user when they're trying to use a machine. This could lead to users ignoring other user's notes. Finally, the use of the word "Claim" is a bit of a misnomer, since our system can't allow a user to actually claim a machine. "View" or "Use" would probably be a better word, and this will be carefully thought about over the next weeks.