CardDroid Math Flash Cards
Available on Google Play (phones, tablets, Android TV), Amazon Appstore (tablets and Fire TV)

First published in summer 2010, this is still my most financially successful app. Total downloads across platforms exceed 150,000. CardDroid Math started as a simple multiple-choice math flash cards app with intelligently chosen multiple-choice options. Initially its unique feature was recorded children’s voices giving encouraging messages in response to correct answers. As the app landscape changed, I upgraded the app to offer multiple color schemes, multiple sound sets, and eventually tracking of missed questions, total practice time, and performance.
I also added simple games as rewards after getting a perfect score and added problem sets aligned to the Common Core education al standards being adopted by many states.

Below are some screen shots. They’re cropped into squares so please click to see the whole picture.

In 2014 I adapted CardDroid Math Flash Cards to run on the Amazon Fire TV (and later Android TV). Take a look at that project here.