You must learn well from lectures - most people do not. I can learn from lectures with great effort but by the third lecture of the day I am reaching saturation. When students are asked to digest six lectures a day, five days a week - I think it is asking too much.
All of us learn differently. Not learning particularily well through lectures does not imply a lack of intelligence - actually it implies that a student will have trouble in school but might do quite well outside of the educational institutions.
Remember the saying "A picture is worth a thousand words"? Obviously this saying does not apply to you, but for the majarity of the population it is true.