In water polo, athletes often swim a combination of freestyle, backstroke and breastroke. Plus, there are other styles of swimming in water polo, such as going backwards to give water while playing defense. Those other styles are taught at the pool and are not in the online course just yet.
Use of stroke count aids in establishing long, big strokes. Get across the pool in a certain number of strokes. Or, take five, seven or ten strokes without stopping.