I'm not sure what law you're referring to. The linked article discusses the implementation of an executive order in Oregon that mostly bans use of cell phones during school time.

Some schools may do things differently, but it seems like the one highlighted in the article allows the kids to keep phone in their backpacks: "Rather than use pouches or lockers, students are allowed to keep their phones safely stored in their backpacks"

I didn't see anything in the article or the text of the EO about confiscation. https://drive.google.com/file/d/1R5kfyMYsA6cg3VQKutUxLTIGVpI...