I was around when mobile phones first made an appearance, I'd been teaching about 6 years at the time, but yes, to answer your question.

For a time, txt spk was constantly appearing in work submitted by kids. A former head of English argued that all languages develop in time (make of that what you will). Upon doing exam marking these past few years, it doesn't seem to have made much of an appearance on the papers I've seen, in all fairness.

Once social media started getting mainstream some 15-20 years ago or so, it very quickly became a serious issue, with kids falling out over absolute dogshit and some kids obviously getting bullied mercilessly online after school finished. This had a massive effect for some kids.

I felt for a time there were serious peaks in in that, although for some kids it was just another distraction, it was at times all consuming for others. Things would flare up at break or lunch because of a misunderstanding like someone posting the 'wrong' emoji, meaning PM lessons would massively go to shit quite quickly.

I have been out a few years now, but at the time, I genuinely think the effects in terms of focus and concentration were generally negative and serious for some, not all.