Overcrowded classrooms and too great a focus on standardized tests scores are among the greatest challenges facing Fairfax County schools, the system’s new superintendent told a gathering of parents Saturday.

“Standardized testing, although well-intentioned, I believe has gone too far,” Karen Garza said, drawing applause from the roughly 650 people in attendance at the fourth annual Fairfax Education Summit at Edison High School. “We need to find new ways we can measure learning and the ways our teachers are teaching without taking the joy out of both.”

In the past five years, the county’s student population has grown by 15,000, and projections show that the school system will continue to expand rapidly, Garza said. This year, the school system expects about 184,500 students to enroll. In recent years, Garza said, enrollment has far outpaced available classroom space, leading to overcrowding and over-reliance on temporary classrooms — including about 990 mobile trailers.

Parents at the event took part in break-out sessions with discussion topics that included spotting the signs of teen depression, supporting children of military families in school, and parenting tips to promote learning at home.

Kevin Sneed, director of design and construction, led a presentation on classrooms of the future and discussed ways to help buildings adapt to student growth.

In a matter of years, Sneed said, Fairfax schools may be equipped with collapsible walls and desks on wheels to allow teachers to rearrange classrooms spaces to better accommodate students.

At Sneed’s discussion, Demeterious Withfield said she was concerned about her daughter, a Hunters Wood Elementary sixth-grader who shares a trailer with 29 classmates.

“They’re not safe,” she said, referring to the trailers. “For security, they should get rid of the trailers.”

Withfield said she hoped that additions such as desks and chairs will help students use space inside schools more effectively.

Terri Breeden, the assistant superintendent for professional learning and accountability, talked about a new test Fairfax high school students may take this year called the Program for International Student Assessment, or PISA, based on an international assessment. Breeden said the new test, used in a pilot program last year in select Fairfax schools, offers innovative questions that help measure students’ critical thinking and reasoning skills. The PISA also helps compare Fairfax students to their peers around the world and could be used in the future as an alternative to standardized tests.

Jocelene Aquino, who has three children in Fairfax schools, said she has lived in Hong Kong and Jerusalem and noticed a disparity in their education systems compared with the United States.

“We’re so far behind,” said Aquino, noting that tests such as Virginia’s Standards of Learning “are an antiquated way to look at educating our children.