### second grade

Single Digit Addition & Subtraction

problem 2: What is the most-polluted city? (page 11)

2 Digit Subtraction

problem 3: How many unhealthy days in our area? (page 20)

problem 4: Got healthier air in Vanderburgh? (page 28)

problem 7: Who has the cleanest car? (page 51)

### Third grade

Single Digit Addition & Subtraction

problem 2: What is the most-polluted city? (Page 11)

2 Digit Subtraction

problem 3: How many unhealthy days in our area? (page 20)

problem 4: Got healthier air in Vanderburgh? (page 28)

problem 7: Who has the cleanest car? (page 51)

3 Digit Subtraction

problem 5: Is our air getting cleaner? (page 34)

### fourth grade

2 Digit Subtraction

problem 4: Got healthier air in Vanderburgh? (page 28)

4 Digit Subtraction

problem 1: Our path to cleaner air (page 7)

problem 5: Is our air getting cleaner? (page 34)

### fifith grade

4 Digit Subtraction

problem 1: Our path to cleaner air (page 7)

5 Digit Subtraction

problem 1: Our path to cleaner air (page 7)