Wordflow Buddies is a practice tool for the SIPPS reading curriculum, offered in partnership with its creator, the Center for the Collaborative Classroom.
Students at participating schools can use the app in conjunction with the SIPPS reading method. The words and lessons in this app mirror the "SIPPS Extension Level" curriculum. The app personalizes each reader's practice regimen based on what it infers about the their particular abilities and weaknesses. 
It allows students to work in pairs, in person or remotely. Students are paired up by their teacher (who does that using the companion Wordflow Insight app) and they take turns: one reads a word while the other listens and assesses the first; then they switch and repeat.