The tactile system is actually made up of two distinct skin senses.

The tactile system is actually made up of two distinct skin senses; protective and the discriminative system. The function of the protective system is to alert us to harmful stimuli. The receptors of the system are the hairs of our skin, head and genitals. The discriminative system is to show us what we are touching, where on our bodies is touching us and what are touching us. The receptors for his system are the hands, fingers, soles of feet and mouth and tongue.

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)