K5 Learning and International Connections Academy both offer online summer school courses for elementary school kids seeking enrichment in core subjects or electives. Admission is usually on a rolling basis and allows for flexibility in scheduling.
International Connections Academy has world language, technology, math and language arts summer school courses for kindergarten through eighth grade students. High school students can enroll in for-credit courses in core subjects or electives, recovery courses for those they've failed at their own schools or technical education classes to help prepare them for the workforce.
K5 Learning's online summer courses are in math and reading. They're interactive with immediate feedback, placement tests and shorter lessons to help prevent kids from feeling overwhelmed, notes K5 Learning.