The learning subjects of primary and secondary levels of educational astronomy appears in cyclic developmental phases throughout education levels. To improve their learnings effectively, it is important to study the correlations of conceptional connection between previous and succeeding learnings, In this study, we select the astronomical unit subjects from the primary and secondary levels of science text books, analysing the conceptional connections between each unit subject and the unit subject of it's previous learning. We finally find that the conceptional connections of each unit are generally well made. Several units, however, have neither connections nor previous learnings which are reexamined, Therefore, we discuss the fitness of intellectual levels of students and the motives of interests to compensate the incomplete conceptional connections.