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If a user has many textbooks, the removed textbooks are pushed down and out of the user’s locus of attention (Figure 2). A user who is unaware of a removed textbook might never learn of the book’s removal until after its deletion because the removed textbooks are located out of sight.
Design 3:
Page 1:
This is the homepage that greets users coming on to the site. The page will have 2 options: for old users to log in with username and password, or for new visitors to sign up by entering a username, email, and password (with a password confirmation). The button at the right of the confirmation password textbox will be labeled "register." If the username is already in use, the page will prompt the visitor to try a different username. After an account has been created, the visitor will have to log in using the normal log in. 
Page 2:
The homepage will enter into "page 2" after visitor successfully logs in. The user now has two options. Clicking the "language go" (name subject to change) button will lead the user to "page 4." The user can also click the "textbook go" (name subject to change) button to enter "page 3." The "language go" button is only available for clicking after the user enters the language in the language drop-down list. The "textbook go" button is only available after the user selects the language, textbook name, and chapter. Note, this will be almost identical in format to the MIT coop textbook selection.
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Page 5:
This page can be arrived on by the user in two ways. The first way is when the user clicks on a hyperlinked tag. The second way is by the user entering tags in the tag search box on "page 4." There are several notable components to this page. First, the Tag: label will contain the tag(s) that were used to take the user to the current page. Next, definitions (translations) will be provided for the Tag in the "Def" field. Below will be a scrollable list of example sentences associated with the tag. Each sentence will have an "edit" (subject to name change) button at the end. Clicking the "edit" button will bring up a pop-up page with three notable components and two buttons. The first component is the Tag List, which has an editable text box containing all the tags associated with the sentence. The user can add and delete tags in the textbox and click the "update" button to confirm those changes. The second component is labeled by the heading "English Translation" and is a translation of the sentence. Finally, the third component is the Tags (hyperlink) component allowing the user to go to more "page 5"-type pages. Clicking the "update" button will also update the hyperlinks available in the Tags field (the third component of the pop-up page). Clicking the cancel button will close the pop-up page. 
Learnability
Pros:
The interface is very simple. The pages are consistent with formats of webpages most people are used to. Most of the pages are pop-ups, so the user can easily go back to previous pages by re-selecting their windows. The existence of cancel buttons give users a more clear understanding of how to exist out of a pop-up page. Certain buttons are only clickable when the necessary fields are completed, enforcing certain actions.
Cons:
Some of the buttons/titles will need additional research/consideration for better names.
Visibility
Pros:
Everything is clearly labeled. The existence of pop-up boxes allow the user to switch views easily. The textboxes, drop-down selection lists, scrollbars, and buttons all provide very visible affordances to the users.
Cons:
A new user might miss the buttons that provide additional information/links to each example sentence. Need to figure out a way to increase the information scent.
Efficiency
Pros:
The simplicity of the design allow users to need only skill-based actions. Pop-up pages save users from having to click back/home buttons to navigate to previous pages. All sentences have a list of hyperlinked tags allowing users to easily obtain more information from sentences without having to open search boxes or type in search words.
Cons:
Lack of breadcrumbs prevents users from tracing their series of actions that led to the creation of the pop-up pages.
Error
Pros:
Pop-up window utilization allows users to explore new pages and features without risk of losing previous pages. No log-out problem, users simply close the window. The interface does a great job of separating states/modes as new pop-up windows.
Cons:
Allowing users to freely modify the tag list of user-contributed example sentences can be dangerous. Does not have a safety for when users accidentally modify and update the tag list field of user contributed example sentences.