1990'1, p.50
Zaytsev . . , Lytko A. A.
Dynamics of 6-years-old first-graders' mental efficiency in connection to their physical activity
(RESUME)

It is found that the increase of 6-years-old first-graders everyday physical activity positively influences their mental efficiency and prevents their wearyness to the end of academic year. There is a drop in mental efficiency of schoolchild-ren towards the middle of academic week regardless of their physical activity. The teachers must take it into account dealing with 6-years-old first-gradrs.