#### First grade

#### Second grade

#### Third grade

#### Fourth grade

#### fifth grade

### First Grade

1-Digit Numbers

problem 23: How much water do I use?

### Second Grade

1-Digit Numbers

2-Digit Numbers

problem 7: Who has the cleanest car?

problem 22: Apple vs. Hamburger: Which takes more water to produce?

problem 24: How can I save water?

### Third Grade

2-Digit Numbers

problem 7: Who has the cleanest car?

problem 22: Apple vs. Hamburger: Which takes more water to produce?

problem 24: How can I save water?

3-Digit Numbers

problem 14: How big is our harmful gas? (using bar graphs)

problem 18: How is our water used?

problem 22: Apple vs. Hamburger: Which takes more water to produce?

problem 46: What state produces the most coal?

problem 53: Wind race U.S. vs. China

4-Digit Numbers

problem 21: How long is our Ohio River?

### FOURTH GRADE

3-Digit Numbers

problem 14: How big is our harmful gas? (using bar graphs)

problem 18: How is our water used?

problem 22: Apple vs. Hamburger: Which takes more water to produce?

problem 26: Global water shortage

problem 53: Wind race U.S. vs. China

4-Digit Numbers

problem 1: Our path to cleaner air

problem 21: How long is our Ohio River?

problem 41: The history of our energy

6-Digit Numbers

problem 46: What state produces the most coal?

Large numbers

problem 20: Water tanks in Evansville

Decimal numbers

problem 5: Is our air getting cleaner?

problem 20: Water tanks in Evansville

problem 48: Our electricity price–high or low?

problem 49: Solar energy in our country

### Fifth Grade

3-Digit Numbers

problem 22: Apple vs. Hamburger: Which takes more water to produce?

problem 26: Global water shortage

problem 53: Wind race U.S. vs. China

4-Digit Numbers

problem 1: Our path to cleaner air

problem 41: The history of our energy

6-Digit Numbers

problem 46: What state produces the most coal?

Large Numbers

problem 20: Water tanks in Evansville

Decimal Numbers

problem 5: Is our air getting cleaner?

problem 20: Water tanks in Evansville