Abstract: Based on the practice of the blended collaborative learning in College Physics course， the quality of interactive content is established according to Bloom's taxonomy of educational objectives in the cognitive domain.It has been found that students' learning achievement in blended collaborative learning is strongly correlated with the quantity of online interaction and the quantity of conventional classroom high quality interaction， the quantity of conventional classroom interaction is weakly related to student learning achievement.

Key words: blended collaborative learning, the quantity of interaction, the quality of interaction, learning achievement