When Baltimore County, Md., public schools began going digital five years ago, textbooks disappeared from classrooms and paper and pencils were no longer encouraged. All students from kindergarten to 12th grade would eventually get a laptop, helping the district reach the “one-to-one” ratio of one for each child that has become coveted around the country. Teaching apps and digital courses took the place of flashcards and notebooks.

Despite the investment, academic results have mostly slipped in the district of about 115,000 students.

Over the last decade, American schools embraced technology, spending millions of dollars on devices and apps, believing its disruptive power would help many children learn faster, stay in school and be more prepared for a competitive economy. Now many parents and teachers are starting to wonder if all the disruption was a good idea.

Technology has made it easier for students and teachers to communicate and collaborate. It engages many students and allows them to learn at their own pace. But early indications are that tech isn’t a panacea for education. Researchers at Rand Corp. and elsewhere say there is no clear evidence showing which new tech-related education offerings or approaches work in schools.

The uncertainty is feeding alarm among some parents already worried about the amount of time their children spend attached to digital devices. Some believe technology is not doing much to help their kids learn, setting up a clash with tech advocates who say technology is the future of education.