The purpose of this study is to examine the effect of density concept learning using block according to Learning Cycle model. The Learning Cycle model has 3 stages, that is exploration, concept introduction and concept application. A total of 39 seventh graders were involved in this study. 18 blocks originally developed by Kohn(1993) were made by specified density although they have various mass and volume. Experimental group were given treatment instruction using the block and Learning Cycle model, while control group were given traditional instruction. After the treatment instruction, there was no significant difference of students` achievement between experimental and control group. Experimental group students felt the Learning Cycle instruction more difficult than control group students did. Students showing active attitude toward instruction have higher achievement score than students showing not active attitude.