In Turkey due to changes in the age starting school implemented during the 2012-2013 academic year, children ages from 60 months to 84 months were subject to the same educational program in the same class. By the 2015-2016 academic year these children were at the end of 4th class. This research aimed to investigate the Turkish and mathematic lesson success, academic self-concepts and self-esteem of 4th class students and determine the opinions of class teachers on this topic. The research used a mixed method pattern with convergent parallel pattern. At the end of the research quantitative findings relating to Turkish and mathematic lesson success according to age starting school and educational level of parents; Turkish and mathematic lesson academic self-concept and self-esteem according to age starting school; and qualitative findings of class teacher opinions were compared, interpreted and discussed in light of the literature.