Open the Pool

It’s the last day of school and your mom says she will take you and your friends down to the city pool. As you arrive at the entrance, you notice that there is a new fence up. You approach the fence to see four locks and a large sign that reads: 

“This pool is closed down until further notice. Only once someone proves their worth will the pool be opened again. We have left for the day but will return right away if someone can open it."

This is no way to start your summer. You and your friends know you can crack these codes to beat the heat and cool down in the pool!