On average among OECD countries, there are about 14 students. per teacher at the secondary level (Table D2.2). As the differences in student-teacher ratios indicate, there are fewer full-time equivalent students per full-. time equivalent teachers at the secondary level than at the primary level of education.
Causes of Lower Back Pain. Home/Conditions/Causes of Lower Back Pain. Pain in the lower back has a multitude of causes. The discs, facets, pars interarticularis, sacroiliac joints, hip joints and nerves can all cause a form of lower back pain.
Acute low back pain is most often caused by a sudden injury to the muscles and ligaments supporting the back. The pain may be caused by muscle spasms or a strain or tear in the muscles and ligaments. Causes of sudden low back pain include: Compression fractures to the spine from osteoporosis.