(1) Pressure from peers who do better generally in terms of academics and socialising, often look down on peers who don't do as good. . . . .
(2) Teenagers whom don't make too many friends often feel lonely and down and that may affect their overall wellbeing. . . . . .
(3) Parents also play a role in the stresses and pressure a teenager faces as they push for teenagers to do well in academics. . . . . .
(4) Teenagers on the other hand, may be distracted by gadgets of the world today, such as mobile phones or laptops, which dramatically pulls grades down. . . . . . . .
(5) Teenagers may also go through this phase known as puberty, this has resulted in peers making fun or mocking peers for they have grown pimples or have body odour. . . . . . .
(6) In terms of concerns, a teenager would be concerned over his/her grades if they are not doing too well and that worrying may in turn harm them mentally. . . . . . . Hope this helps ;)