For a few years now, the words rigor and engagement have been tossed around as a best practice in teaching, but Mr. Antonetti put some sense to the words. Finally, someone put the two words together to give them meaning (Or mayhaps this has always been the case and I missed it.).
Engagement is when the work has meaning.
Cognitive engagement (rigor) is when the learners make meaning.
Rigor is not hard; it is new.
Rigor is not more; it is me.
Rigor is not long; it is learning.