BG 1.3 'A śloka a day' #SAH #Grammar

पश्यैतां पाण्डुपुत्राणाम् आचार्य महतीं चमूम् |
व्यूढां द्रुपदपुत्रेण तव शिष्येण धीमता ||3||

paśyaitāṃ pāṇḍuputrāṇām ācārya mahatīṃ camūm |

vyūḍhāṃ drupadaputreṇa tava śiṣyeṇa dhīmatā ||3||

Behold, O teacher, this great army of the sons of Pāṇḍu, arrayed [in battle formation] by your wise student, the son of Drupada 

आचार्य ācārya O teacher (vocative; note no visarga)

पश्यैतां paśyaitāṃ (पश्य एताम्)  

पश्य Look (at), perceive; (2nd person, imperative, active √paś) 

एताम्  this (fem, acc, singular - refers to the army)

पाण्डुपुत्राणाम् pāṇḍuputrāṇām of the sons of Pāṇḍu (masc, genitive, plural)

चमूः (fem, noun, sing)
महतीं चमूम् mahatīṃ camūm [look at the] great, mighty army (fem accusative)
व्यूढां  vyūḍhāṃ [the army] arrayed in battle formation (fem, acc, sing past passive participle vi √vah adj for  चमूः )

द्रुपदपुत्रेण  drupadaputreṇa by the son if Drupada (masc, instrumental, sing)

तव tava your (genitive, sing) 

शिष्येण  śiṣyeṇa by your student

धीमता dhīmatā [by] wise, intelligent adj. for Drupadaputra

Please note the agreement between the nouns and adjectives:
एताम् व्यूढाम् महतीम् चमूम् (feminine accusative singular)  
धीमता शिष्येण द्रुपदपुत्रेण (masculine instrumental singular)