Hey Aureli, I think "Lisa couldn't see the point of learning to sew." is fine. it's also correct. good job

Perhaps your book is teaching you British English? In American English, you can say both "the point of" and "the point in". British English is different than American English in many ways, especially with prepositions. Take for instance, the British phrase "at the weekend" versus the American phrase "on the weekend". Also in UK English, someone plays "in a team" but in American English, someone plays "on a team". In British English, you say "enrolled on" but in American English you say "enrolled in." For instance, "He is enrolled on that class." (British English) but "He is enrolled in that class." (American English) For more of these differences see the Wikipedia article on the comparison of American and British English. The article is located here: http://en.wikipedia.org/wiki/Comparison_of_American_and_British_English#Divergence

My dictionary tells me that the correct phrase is 'to see the point IN doing something. So, the sentence should be: Lisa couldn’t see the point in learning to sew.