Unit 7, Section 3.1 explains, 'We use a.m. (ante meridiem) to show that the time between midnight (12 o'clock at night) and noon (up to 11:59 at midday).'
Class 4 › English For Today › Chapter 5: 5 - 8 Unit › Topic: Telling time using a.m. and p.m.
Aligned to the NCTB national curriculum.