Purpose: Attention is a significant factor for the learning process, and it may affect the degree and efficiency of student’s learning and their teaching. Methodology: Therefore, the present paper aims to examine the effect of the fluctuations in daily and weekly rhythms, and chronotype (morningness-eveningness) on the attention performance of preschoolers. The research’s methodology is a causal-comparative one. The statistical population includes 100 preschoolers in Tehran who were selected by purposeful sampling. They were tested in different hours of day (8, 11, 13, and 15) and weekdays (Saturday, Sunday, Tuesday, and Wednesday). Findings: The data were analyzed by mixed analysis of variance. The results show that preschoolers’ performance is different for different days of week and hours of day (p<0.01). |and in comparison with the attention performance of evening and intermediate types, that of morning type shows no significant difference in educational environment during day and week (p<0.01). Discussion: The practical implications of these findings for the planning of school schedules are benefit.