The contents of natural science in Japanese elementary and high schools are changed accordingto the revision of the school curriculum guideline. In this paper, we study the variation of contents in elementary and junior-high schools by the revision in 2008. We find that the contents increase, and we argue that students can learn science more systematically according to the revision. We confirm that the most of the ""new"" contents were actually present in the revision of 1989, but they were not included in the revision of 1998. For each content, the school year is specified in the guideline, and the year has changed for some contents. We find that several contents have brand-new subjects that have not been included before, i.e. ""animals and plants in the backyard"" in elementary, ""DNA"" and the ""Galaxy"" in junior-high, and ""safe education"" (chemistry) in both elementary and junior-high schools. We note that one should take much care to those brand-new subjects before teaching them. We alsodiscuss some aspects of classes of teachers' training course in Kagawa University.