Juku is supplementary schooling for elementary, junior, and senior high school students. They are often referred to as “cram schools” in the West. Most may think of juku as being run by large commercial enterprises with chain across the nation but not all are like that; some are run by a neighborhood for their children or is a small establishment with a few students. They are mostly attended later in the day after students are done with their classes and are more intensive than regular classes.
Subjects can range from math, science, social studies, and other school-related subjects. Most students attend a juku to receive help, support, and supervision in passing their current studies. The academically advanced, though, can receive accelerated materials or enriched programs while middle school and high school are more geared towards entrance exams for a high school or college, respectively.
In Maiko Covington’s article about juku’s, it states that there are even American juku’s in Japan. Details are a bit sparse about what is done in those American juku’s but I suppose they’re much like other juku’s with a American orientation in subjects or speaking. Speaking of America, there are numerous “juku-like” institutions in the US such as the Princeton Review, Kaplan Learning, and Kumon Learning Centers. Both countries also make use of private tutors for specific subjects. As expected, it’s usually the more affluent families that can afford private tutors and juku for their children. Some mothers actually take up part-time jobs so they can pay the juku fees for their children if the family income is insufficient. Taking up a part-time job for this reason is actually considered a valid answer when applying for jobs in Japan.