The game is mainly for primary school grade three，corresponding the third grade fifth unit of
primary school mathematics of Human education-- rectangular and square area calculation.Games of QD learn are developed specifically for primary school education ,both educative and entertaining.Game design is supported by educational theory.One game one knowledge point.Multi angle interpretation.Repeated practice of different forms of investigation.Play and learn focus.Master difficulty in interest.Proficiency test.QD learn aims at teaching through lively activities and happy learning.