Van Cortlandt Park turned into an outdoor classroom on Tuesday for a group of students learning about local waterways.

The "Seeds to Trees" program, run by the City Parks Foundation, gave students an opportunity to learn more about their environment through hands-on activities that connected them to nature.

During Tuesday's lesson, fourth graders from P.S 18 learned to find and examine organisms large enough to see with the naked eye to determine how clean pond water is.