the alert student...

काकदृष्टिर्बकध्यानम् श्वाननिद्रा तदैव च।

अल्पाहारम् जीर्णवस्त्रम् एतद् विद्यार्थिलक्षणम्॥

नीतिसारे॥

kākadṛṣṭirbakadhyānam śvānanidrā tadaiva ca|

alpāhāram jīrṇavastram etad vidyārthilakṣaṇam||

nītisāre||

काकदृष्टि the keenness of vision equalling a crow

बकध्यानं concentratin of mind comparable to a crane

श्वाननिद्रा the alertness during sleep like a dog

अल्पाहारम् frugal food

जीर्णवस्त्रम् tattered clothes

तदैव च एतद् all these

विद्यार्थिलक्षणम् (भवति) are the signs of a student or someone undergoing a process of education//

This is a very celebrated slokam defining the characteristics of a good student..

The qualities should not be interpreted to compare with the apparent features--like the transparent diaphragm on the eyeballs of a crow, the long and supple neck of a crane or the fluttering of the ears of a dog when it sleeps, the food and clothing habits of a man afflicted with poverty and so on..

The slokam just means

A student should have the keenness of observation like a crow..

A crane sits on the banks of a tank without movements and in utter concentration, watching some fish to surface and then makes a decisive movement..

The student should posses similar purposeful concentration

Dogs are famous as sentinels because their capacity to trace movements, sounds, smell etc even while sleeping is very acute.. A student should have such keen senses even during his sleeping hours.

The taste and craving for food is natural for man, and excessive appetite would push all other matters deserving attention to the background. A student is expected to prioritize of learning things at the shorted possible timespan.. and he shoul be alert and fit physically.. Desire for gourmet food and consumption of excessive food both can make him less alert and more flabby.. So the student should restrict food.. And in the Indian environs of the days when the above sloka originated, the students were not exactly affluent (on an average) and they were staying with the teachers. The teachers had to find food for the students, or alternately the students would beg in local households for food.. In such circumstances availability of food was a real issue..

Celibacy was somehow considered as a prerequisite for a student.. And wearing costly and attractive Garments, applying cosmetics etc were taboo for students for that reason and for the economic reasons too..Brahmacharis are not expected even to look at the mirrors to see their forms..This is the idea behind wearing tattered clothes.