4th Grade Math Worksheets Money Puzzle and Riddles (4.MD.A.2) - These worksheets are fun and really applicable to everyday math. Operations With Units of Measure Worksheets (4.MD.A.2) - Do not let the presence of units muck up your understanding of what is going on. Metric Units of Volume (4.MD.A.2) - The liter is the most common unit you will find here.