Accessibility
What this course does so it can be read and worked by more people, in enough detail that you can tell before you start whether it will suit you. Where something is missing, it says so.
Theme and text size
Day and night. The switch sits in the header on every page and the choice is remembered on your device, so you set it once.
The Aa menu offers text at 100%, 125%, 150%, 175%, or 200% and remembers that choice too.
Your choices are read and applied before the page paints, so it never flashes the wrong ground or text size at you first.
All three themes are one set of colour names solved three times rather than three separate designs, which is what stops a corner of the site from staying light when everything else has gone dark.
Colour never carries meaning on its own
Everywhere this course marks something — a correct answer, a missed one, a module, a completed unit — the colour is accompanied by a word, a glyph, a fraction or a position. If two hues are indistinguishable to you, nothing on the page becomes unreadable and no exercise becomes unanswerable.
Text is set to clear a 4.5:1 contrast ratio against the surface it sits on, in both themes.
Motion
If your system asks for reduced motion, animations and transitions are cut to effectively nothing across the whole course. Nothing here moves on its own, nothing hijacks your scrolling, and no exercise advances you to the next step before you say so.
Keyboard and screen readers
A skip link is the first thing on every page, so a keyboard or screen-reader user can jump past the header to the content. Focus is always visible, because a focus ring that exists but cannot be found is not a focus ring.
The interactive exercises drag things into places, and every one of them can be worked three ways: drag with a pointer, click the thing then click where it goes, or focus it and use Enter or Space, with Escape to put it back down. What you picked up and where it landed are announced, so the exercise is followable without seeing the board.
The tools that act on selected text — highlight it, look a term up, keep the passage in your notebook — watch the selection itself rather than the mouse. Selecting with Shift and the arrow keys, or by dragging a phone’s own selection handles, offers you the same three actions a mouse drag does.
Reading length is yours to set
Course readings are served one part at a time by default, with a strip to jump between parts. If that suits you badly — a screen reader, a print-out, or simply wanting the whole argument at once — “Read the whole lesson” lays it all out, and the choice is remembered.
Nothing completes itself because you scrolled. Marking a unit complete is always something you do deliberately, so a meter can never claim you have read something you have not.
On papers, footnotes render as margin notes when the window is wide enough, and that is a switch in the paper header rather than something imposed on you. The footnotes stay in the document itself either way, so nothing is only reachable through the margin.
What is not done yet
This page is a description, not a conformance claim. The course has not been through a formal WCAG audit or tested end to end with a screen reader by somebody who uses one daily, and until it has, that is the honest state of it.
Two known gaps: the exercises are visual boards, and while each is operable by keyboard and announces what happens, a few of them convey spatial relationships that no announcement fully replaces. And the course quotes real reports, several of which are PDFs on other people’s sites whose accessibility we do not control.
Tell us what breaks
If something here blocks you, that is a defect and we want the report. Open an issue at the course repository, which is public, or write to xlab-info@uchicago.edu. Say what you were trying to do and what got in the way — that is more useful than a standard name.