ST. PETERSBURG — It's a cloudy day, but that doesn't stop the two students from examining the black-and-white disk in the water, letting it sink far enough until they can no longer see it.

The tool is scientifically known as a Secchi disk because of its creator, Italian astronomer Angelo Secchi, who first discovered the item as a way to measure the visibility or transparency of water. The students have never seen something like it, and they marvel at being able to retrieve this kind of information from a disk attached to a rope.

Janautica Farmer, whose very name implies a desire to be on the water, is one of these students, a 16 year old who had never been on a boat. She has a quiet voice, one you have to lean in to fully hear, but she speaks with conviction. And she's been in the Associated Marine Institutes Kids Program in Gadsden County near Tallahassee for about a year, a program focused on helping children with a troubled past "achieve a bright future," according to its website.

"It's opened me up," she said. "I used to be quiet and anti-social. I didn't used to talk to anybody. But it makes you social. You have to talk."

Part of the "floating classroom" experience, as AMIKids calls it, is conducted through a partnership with Mote Marine Laboratory, which works with the nonprofit as part of a community engagement mission. The excursion on Tampa Bay included Mote's marine science educator, Kayla Keyes, who was on deck Friday to teach students, some from Gadsden County and others from Pinellas County, about estuaries, mangroves and the tiny discoveries in something as small as looking at sand beneath a microscope.

"You never know what sticks," Keyes said of working with students. For her supervisor, it was a fear of sharks that turned into a love of marine science and studying sharks.

In the case of at least one student, Pinellas County eighth-grader Lathen Gentner, there was definite, wide-eyed interest. As Keyes removed a fully intact manatee skull from her box, she opened the mouth to show the animal's teeth. Gentner chimed in.

"They're vegetarians," Gentner said, lightly touching the teeth so they would not fall out of the skull. "They don't have sharp teeth, because they don't have to eat meat."

Keyes nodded enthusiastically. Perhaps there was a future marine biologist in the making.