The problem is that the phone is right there - that's basically it. When you need a computer for studying but you already have a source of entertainment in your hands, your brain picks the easy way out. Taking the phone away during lessons is the right call, but you need to frame it as a condition, not a punishment. It's best to agree with your son beforehand - maybe even suggest he put the phone in another room himself before classes start. Give him a sense of control over the situation, not the feeling that he's being caught.
At the same time, it's worth figuring out why lessons seem boring to him compared to TikTok. Maybe the material is too hard or, on the flip side, too simple? Talk to his teachers - find out which subjects he's losing focus on. Sometimes it helps when your son becomes part of the process: let him pick a convenient time for studying, allow him to take breaks when he asks for them himself. If he understands that he has a say in this, motivation usually goes up.
One more thing - check if he's getting enough movement and real-life interaction during the day. Kids who sit and study online all day often look for stimulation on social media. Maybe sports, walks, or even just more conversations with you will help him concentrate better on his lessons 😊