Open Yale Courses has made professors’ lectures available to Internet users around the world, but it is also changing how those professors teach on campus.

The website, which now features videos and transcripts for 35 Yale courses, launched in 2007 in an effort to broaden access to a Yale education. But in some cases, the program has led to revisions in a Yale education: many professors whose lectures are posted online have since altered their courses to avoid redundancy and give students a reason to attend class in person. While many professors have changed the topics they cover, others have completely redesigned the structure of their classes and incorporated the online material.

Ecology and evolutionary biology professor Stephen Stearns and religious studies professor Christine Hayes both require their students to watch their online lectures before coming to class so that they can spend class time on discussion. Many students interviewed complained that this format makes the courses much more time-intensive, but some said they appreciated the chance to engage actively with the material during lecture.

Diana Kleiner, the founder and director of Open Yale Courses, said she expected that the creation of the site would cause professors to re-evaluate their teaching methods. As an art history professor whose course “Roman Architecture” is online, Kleiner said she worried whether students would skip class and watch the lectures on their own time. But she said she feels that the process of filming courses allows professors to reflect upon and improve how they present material.

Stearns modified his course “Principles of Evolution, Ecology and Behavior” this spring after students complained in course evaluations that his lectures were “too similar” to what was available on the Internet, he said. He now spends most of class asking students questions based on his online lectures and introducing some new material, he said, which allows him to conduct the large lecture course in “section mode” with more student participation, though sections with teaching fellows are still offered.

But his new approach has generated mixed reactions from students. While two of nine students in the class interviewed said fielding questions during class better prepares them for exams, many students said they struggled to find time to watch the online lectures and then felt lost in class when the material was not covered.

“If he just asks questions, he’s not teaching,” Leen van Besien ’14 said. “He’s just quizzing us.”

Stearns, whose course has over 100 students, said he intends to continue tweaking the course format in response to student feedback.

While Hayes, who teaches “The Bible” in the fall, has also asked students to watch her online lectures in advance, she said she spends the beginning of each course covering the main points of lectures before turning to close reading of texts. Hayes’ course typically draws around 50 students and does not have a discussion section component.

She said she realizes that the course is a lot of work and “turns into two courses in one,” but that she has received “very positive” student responses.

“Once it went online, I thought, ‘I’m not going to stand here and give the same lectures [students] can watch at home,’” she said. “That’s just not very interesting for me to do.”

Four students interviewed who took Hayes’ course last fall said her approach allowed them to delve into biblical texts more deeply since they had the information from her online lectures as a foundation. All four praised the course, though they said it was considerably more work than other courses and that watching the online lectures was essential in order to keep up.

Six of 10 other professors whose classes are featured on Open Yale Courses said they have changed their courses to avoid repeating material available online. Religious studies professor Dale Martin said a steady drop in enrollment in his introductory course on the New Testament after the course went online prompted him to stop offering it. Instead, he modified half of the syllabus to create a new class, “The New Testament in History and Culture,” which has been more popular, he said.

Other professors said they are partly motivated by a desire to avoid repeating the online lectures when they update course material to incorporate new research in their fields.

Kleiner said she has not noticed a trend in changes to course enrollments after classes were posted to Open Yale Courses, adding that many factors can influence student demand for courses.

The Open Yale Course website has received 3.5 million unique visitors since it went live in 2007, Kleiner said.