Respected sir,

The age criteria required to join in 6th standard in CBSE Board School is 10 years 6 months as on 31st March of the year of admission. Your grand-son should have passed 5th standard from a recognised board to get admission for pursuing 6th standard in CBSE Board School. Since, your grand-son was born on 19-03-2012, he is 10 years old at present, so, he will be eligible to get admission in 6th standard in CBSE school for the academic year 2022-23.

Hope it helps you..

Best of luck..