All NROC-produced videos (for Algebra 1--An Open Course and Developmental Math--An Open Program) are closed captioned.
The SIATech content on the English page is closed captioned, as is NOAA's "Oceans Today" from the Earth Science page.
The simulations and interactive activities--PhET, Concord Consortium, Dallas simulations, and Math Snacks games--don't have any narration, so closed captioning would be moot.
The remainder of the content from our Collections partners is not closed captioned.
For a detailed list of the content that is Closed Captioned see this document.