The purpose of this study was to verify the validity of shifting between grades by analyzing achievement and the knowledge state analysis method on photosynthesis-related concepts in 7th and 8th graders. To do this, we had the 7th and 8th graders take the test on photosynthesis-related concept items and checked their achievement. On the basis of their test result, we draw up the hierarchy using the knowledge state analysis method. The result shows that the 7th and 8th graders` achievement on photosynthesis didn`t have meaningful difference between the two graders(p>0.05). However, the achievement of 7th and 8th graders after the class increased compared to the before class(p<0.05) and it means class has positive effect on the concept achievement. Pre- and posthierarchy of concept of 7th and 8th graders has overall similar aspect. From the total hierarchy of concept, the concept on the place of photosynthesis placed low, the concept of plant nutrition placed high, and the other concepts placed in the middle. According to the result, we can say that shifting between grades of photosynthesis is appropriate.