Math Worksheets For 1st Grade | 1st Grade Online Math ... 1st Grade Online Math Worksheets. According to the Common Core Standards, in Grade 1, instructional time should focus on four critical areas: (1) developing understanding of addition, subtraction, and strategies for addition and subtraction within 20; (2) developing understanding of whole number relationships and place value, including grouping in tens and ones; (3) developing understanding of ...