nessy.com is an excellent OG-based reading & writing online self-paced curriculum family with skills through the end of elementary school (K-5 reading, 1-6 spelling). It has the bonus feature of having been developed in the UK, so the original version can be used by our friends in Commonwealth countries. (When I first looked at it a few years back, it was in British English only.)
If we are talking specifically about filling instructional gaps as we emerge from COVID, then Nessy would be a good option for language arts foundations.
And there's also Reading Horizons/Elevate. Also an online OG reading intervention (I'm listing mostly OG reading programs because why not pick something that works for almost all learners?).
Lexia has a number of online, self-paced, evidence-based programs for K-5 reading.
Last edited by aeh; 03/25/21 05:26 PM.