Final answer:
To properly wash hands, about 5 mL (1 teaspoon) of liquid soap should be applied and rubbed all over the hands for at least 20 seconds, focusing on commonly missed areas. A teaspoon of soap is approximately 4.93 milliliters.
Step-by-step explanation:
To properly wash hands, a student should apply about 5 mL (1 teaspoon) of liquid soap and rub it all over their hands for at least 20 seconds, making sure to wash commonly missed areas such as the thumb, wrist, areas between the fingers, and skin under the fingernails. The volume of soap required can be measured using a teaspoon, which is approximately 4.93 milliliters. So, using a teaspoon of soap would be sufficient.