Swimming schools provide swimming lessons and aquatic instruction for children and adults, from beginners who are learning to feel comfortable in the water to more confident swimmers developing their technique. Lessons commonly take place in swimming pools and are arranged by age, ability or experience. Teaching may cover water confidence, floating, breathing, safe entry and exit, and the main swimming strokes, with progress assessed as skills improve. Many schools offer group classes as well as one-to-one tuition, and some run parent-and-baby sessions, adult beginner lessons, stroke-improvement classes or instruction for people with additional needs. Courses may include guidance on water safety and survival skills, such as treading water and reaching safety. Lessons are usually led by trained swimming teachers, with class size, facilities and the range of courses varying between providers.