I'm working on a preschool project, which will have 30 babies between 4 months to 1 year-old; 30 babies between 1 to 2 years-old; 30 babies between 2 - 3 years-old; and 30 babies between 3 to 4 years-old. How should I develop the water calculation for these "students"? Should I include all babies as "students"?