Which of these factors would you blame for a lack of student achievement?

I don,t believe that children are achieving less.I have three children from 20 to 12 and I believe that teachers are generally better than in my time. There is still no good system for weeding out the poor teachers which of course still exist. I feel that my children are not as able in some things as we are but more able in others.They certainly have much more work to do and there are higher expectations for them both from school and pushy parents.I feel their lives are more pressurised, but that it is preparing them for what the world is like now. I would not like to swap places! (in uk)