My Take
I love this website and use it all the time with all of my classes, K to 5. I find that even though it is Brainpop Jr. my students in grades 4 & 5 enjoy and learn from it. I am at a Title I school and regular Brainpop was often above the students and I would end up doing a lot of pre and re teaching of concepts, with Brainpop Jr. I do not need to do this.
I love the program and when asked whether we need to renew it each year I quickly say yes. It is one of the databases I do not want to loose.
One thing I do not like is that the students have to login. In my district most of our databases are IP authenticated within the district meaning the students do not need to login to access them. Getting the younger students to login can be very time consuming which is why I usually do it whole class for them.
How I Use It
I have done it as whole class with written quizzes and individual with online quizzes. I have had the whole class do the same subject and allowed the students to choose within a group such as Famous Women during Women's History Month.
All of these have worked well.
I love the vocabulary, the online quizzes, the additional information, activities, games, etc. I can usually find something for everyone. With hard and easy quiz options I can decide which the student or grade level should do. I can also print the quiz and use it to direct the students when listening to the video.