This digital copy of Finding and Correcting Errors Whole Number Computation offers an efficient, diagnostic method utilizing skills trajectories to identify misconceptions in addition and subtraction computation. Larger skills are broken down into small steps. A pre/post assessment identifies where students begin to struggle, and problem sets for each step are provided. A tracker allows easy groupings of students around skill levels and celebrates movement along the trajectory. Ideal for home schooling, classroom, or intervention use.