The phrase "supplementary class" is correct and usable in written English.
It can be used in various contexts, but it generally refers to an additional or extra class that is offered in addition to the regular curriculum to provide extra support or instruction. Example: I struggled with math, so I signed up for a supplementary class to help me improve my understanding of the subject.
Some local universities offer supplementary classes to high-school students.
I came to Princeton with the ambitions of a naïve first-year student, wanting to go to all the guest lectures, sponsored study breaks, supplementary classes and more.
The Stephen Lawrence Centre, which has a Chris Ofili abstract design embedded in its floor-to-ceiling glass façade, offers supplementary classes for high-school students in a tough neighborhood in South London — Stephen Lawrence, an eighteen-year-old black youth, was murdered by a gang of white racists in 1993.
CCA costs international students about $50,000 per year, which covers tuition, a home stay, supplementary classes in English and global history, and fees for EduBoston and consultants in China.
A year after the United States Supreme Court ruled that public school teachers in New York City could hold remedial and other supplementary classes inside religious schools, rather than in oversize vans off the school grounds, school and union officials say there have been no complaints from those teachers.
For example, one study reported that ALEKS in an after-school program offered gains comparable to expert teachers running supplementary classes, but with lower burden on facilitator/teacher time (Craig et al. 2013).
Research and personal experience has taught me that Ivy League college admissions officers like applicants that are well-rounded and demonstrate ongoing commitment to both their studies and extracurricular activities: play the same sport for 4 years, master the guitar, pursue supplementary classes to make up for a poor grade in your weak area, or start your own club or organization.
The daycare service will provide activities of different school clubs, as well as educative and supplementary classes, placing special emphasis on literacy programmes supported by school teachers and representatives from the Department for Education of Brcko District Pupils or Students from Prutače school often come from dilapidated houses and buildings, living under difficult conditions.
Audio- and video-based language laboratory program coordinated with and supplementary to class work.
Then, the M7 (beta distribution of ω ratios, with 0 < ω < 1) versus M8 (extension of M7 with a supplementary site class with ω > 1 estimated from the dataset) comparisons were done to test for positive selection among sites.
