This spring, the BioEYES program celebrates a major milestone: It will serve its 100,000th student.

That means in the 14 years since BioEYES began, 100,000 elementary, middle, and high school students from Philadelphia and four other sites have been exposed to innovative, hands-on lessons that get them excited about and interested in science.

That’s a lot of students. And that’s a lot of zebrafish.

The zebrafish are at the center of the BioEYES program: Live fish are brought into the classroom, and for a week, students observe the embryos and larvae, recording what they see, hypothesizing and testing ideas, and asking questions. In short, they learn to think and act as scientists do.

“Students get to be scientists and not just learn from scientists—they have to take ownership of the scientific process,” explains Jamie Shuda, director of outreach and education at the Institute for Regenerative Medicine, and the co-founder of BioEYES. “We’re across grade spans but we are specific to what teachers have to teach. It’s not an addition, but a complement to what we’re asking students to master.”

Shuda says the program began as a grassroots collaborative effort between herself and scientist Steven Farber—who worked at the time as a faculty member at Thomas Jefferson University. It has been supported by local organizations, including the Brook J. Lenfest Foundation, one of BioEYES’ earliest champions. Shuda recalls bringing fish into the classroom herself, and creating workbooks for students as a word document on her computer. She says she even went directly to the School District of Philadelphia’s main office with zebrafish in tow to advocate for the program.

Now, the curriculum is more formalized, and the program has developed a model teacher initiative. For two years, BioEYES staffers visit classrooms to lead lessons; after that time, teachers can sign up to lead the BioEYES program in the classrooms themselves. Shuda says this has enabled the program to expand exponentially and build a robust network of educators.

Today, the program serves second-, fourth-, and seventh-graders (which will switch to eighth-graders next year because of a curriculum change in Philadelphia schools), as well as ninth- to 11th-grade biology students.

In addition, BioEYES has expanded to include sites in Baltimore (based at the Carnegie Institution for Science, where Farber now works); South Bend, Ind.; Salt Lake City; and Melbourne, Australia. Per year, the Philadelphia and Baltimore programs serve about 250 second-graders, 1,200 fourth-graders,  2,700 seventh-graders, and 3,100 10th-graders.

For more than 10 years, BioEYES has been a part of the fourth-grade science curriculum at Solis-Cohen Elementary School, located in Northeast Philadelphia. Fourth-grade teacher Sande Yeck says her students may not initially be interested in science, but on the first day of BioEYES, their attitude changes.

“They really become scientists—it’s not like they’re playing scientists—these kids are really recording observations, they’re comparing notes, they’re learning,” Yeck says. “When this program comes to the classroom, it creates an anticipation and excitement. [They ask] ‘Can we look at our fish?’ They are just so excited.”

Yeck explains BioEYES staffers bring several adult female and male zebrafish to the classroom, and small groups of students observe the fish, guessing which is female and which is male. The next day, BioEYES staff collect the adult zebrafish, and students use magnifying glasses to see if there are eggs in the tanks. If so, they use pipettes to carefully remove them and put them in a petri dish with a nutritious medium liquid. Students are able to use a microscope (provided by BioEYES) to see the changes in the zebrafish as they grow.

Shuda says zebrafish are an ideal organism for the one-week program because they grow from a two-cell embryo to a free-swimming larvae in five days. Plus, they are transparent, so students actually see the blood flowing and a heart beating in the fish. They can even see the zebrafish’s backbone.

“Science is constant communication and questioning,” Shuda says. “It’s not as linear as you make a hypothesis and figure out whether it’s right or wrong. Different questions are asked depending on what grade level. Every day they have to collect data, discuss the data, and see what the data is telling them.”Yeck says BioEYES speaks to the different strengths of her students and gets them to work cooperatively and collaboratively.

“Just seeing the excitement, I think it’s motivated me to try to provide more hands-on opportunities for the kids,” Yeck says.

Shuda says she’s come across students in other aspects of her work who have been moved by BioEYES, both in the city-wide Carver Science Fair, where she is a committee member, and in an Academically Based Community Service course, where one student cited genetics lessons from the BioEYES program as the reason she was sitting in the Penn classroom. BioEYES has also served as a catalyst for students to discover their interest in science as a career. Last year, the Institute for Regenerative Medicine at Penn awarded summer lab internships to two students who credited their love of science to their experience with BioEYES.

“This type of exercise is so unique in comparison to what students get on a daily basis that it just sticks with them,” Shuda says.

Shuda hopes to keep growing the program, not only in numbers of students, but in the depth of the experience.

“I never thought that it would be my path to connect the University and local schools through science,” she says, “and that I would be able to build something with such a great group of people who are experienced not just in science, but in education.”