Thanks to Piano Geek Week, I just discovered another great resource for a more gradual approach to sightreading practice - Diane Hidy's Sightreading Flashcards.
I plan to add these to my teaching binders along with my Pianimation sightreading sets & use them with my Consecutive Sightreading Contest that I posted about here. She has 14 free sets (4 pages each) that begin with