In one experiment, students told they would have to teach a passage remembered it better, and in a more organised way, than those expecting a regular test. Preparing to explain forces you to structure ideas and quickly exposes the fuzzy bits. Explain your notes out loud to a friend, or even to an empty chair.
Chlorine on its own is fairly gentle. But when it combines with urine, sweat and other grime from swimmers, it forms chloramines, which cause stinging eyes and that classic 'chlorine smell'. A well-kept pool barely smells at all. Shower before you swim and never pee in the water.
Muscle mass slowly shrinks with age, putting independence at risk. But in 1990, a study had nursing home residents aged 86 to 96 train their legs for eight weeks: their strength more than doubled. Muscle responds to training at any age. Getting up from a chair without using your hands is already an exercise.