Workouts. Student workouts for addition; Student workouts for subtraction; Student workouts for multiplication and division; Student workouts for proportions and percents -- Teacher-directed activities. Problem strings. Addition; Subtraction; Multiplication; Division; Fractions; Percents; Solving proportions -- As close as it gets. Addition and subtraction; Multiplication and division; Fraction addition and subtraction; Fraction multiplication and division -- Relational thinking. Addition; Subtraction; Multiplication; Division.