I would still disagree about phone usage.
Even when in school, phone helped me quite a bit with education. Having a way to do a quick fact-check is invaluable.
Now as I'm finishing getting my degree such devices became an inseparable part of the process.
Yes, you may not always listen to what's being said whilst using them, but lets be frank, you wouldn't be listening to those parts either way.
School education in a lot of places is fundamentally flawed. It's extremely difficult to learn when you're expected to absorb information just by listening and writing.
I'd agree with OPs sentiment here, off-topic smartphone usage isn't the cause for worse education, but instead is a result of poor engagement in the first place. Should people be more engaged in the topic then suddenly smartphones start being used as a studying tool and not for entertainment. There are many ways of achieving that, but that's a whole different story.
"fact-checking" was a bit of a crude way of putting it on my part. I'm not native, so there could've misused it.
(Went a bit overboard with a wall of text again, but of well)
Although it wasn't without the fact-checking in it's normal sense. Take "English as a foreign language", for example. One teacher will say the word is pronounced one way, the other will say its different. Who's right? Let's check Cambridge dictionary. Although it isn't always teacher's fault as a professional. Sometimes you just forget things no matter how well you know them.
The other part that I may have failed to convey is looking information up, be it a math formulae, a word, some sort of rule, name or a date.
It's way quicker than going through your books and is actually not a bad way to remember something. You either have a tab left off or you're seeing it when using the search, which makes you remember that you did look that up a while back. It's very minor, but because you're still being reminded about it from time to time, the information sticks. Essentially you're doing unintentional passive memorisation.
That's why I think that maybe not in primary, but definetly in secondary and high school banning technology is not the way to go about it. If the student uses it for entertainment during class, they won't suddenly start studying if you prohibit them from usining it. You're essentially solving a non-issue, because the majority of students aren't even using phones during classes (Well, maybe to cheat on tests, but that's hurting the quality of assessment and not education itself).
Banning phones is easy, but it's also the least impactful thing you could to to "improve" educational system. It would be of more sognificance you were to reduce classes to 8 pupils, lessen teacher's paperwork, introduce new active teaching practices, reward students for persuing their endevours and so on. But that's difficult, banning phones is easy and brings you more polical approval.