Ivan, a teenager, is most likely to expend high levels of concentration and interest when he is:

When Ivan is most likely playing sports.

Most likely in the age of Ivan is he more active and playful which explains why he is more engage in physical activities and rarely in academic ones. Further, this explains why his levels of focus and interest is high when engaged in physical exercises. 

Afine-grained igneous rock forms as a result of slow cooling.

France played a key role in the american revolutionary war (american war of independence; 1775–1783). motivated by the ideals of the new nation which were inspired by the french enlightenment, as well as its long-term rivalry with britain and so as to avenge their territorial losses during the french and indian war, france secretly began sending supplies to the americans in 1775.