参加型の講義って英語でなんて言うの？

An interactive lecture or any interactive experience, is one in which the people that are present are actively involved in some way. They may be required to speak, or participate in some other way, to complete the delivery of the activity.

Interactive = all those present actively participate.
Student participation = the students must take part!
In the classroom. Classroom activities guided by the communicative approach are characterised by trying to produce meaningful and real communication, at all levels. As a result there may be more emphasis on skills than systems, lessons are more learner-centred, and there may be use of authentic materials.

When something is described as being "involving" it means that it requires active participation similar to the use of the word " interactive.

A class where the students participate is called a seminar. This is a class which often follows a lecture and has a smaller number of students with a teacher where they can discuss the subject of the lecture.

"Participation" is when you have to take part in something
"Interactive" is when information is flowing back and forth