I wrote:

On the morning of Christmas we went to grandmother's house.

My teacher insisted that 'In the morning..' is correct and mine is wrong.

Please help.

The best answer is "On Christmas morning".

To my ear, "On the morning of Christmas" and "In the morning of Christmas" both sound a little unusual. Given the context, I prefer "On the morning of...", but I judge both to be grammatically acceptable.

The term "the morning" does attract "in" more than "on", but adding "of Christmas" does make a difference in this case. I can only offer the experience of my native ear, and it tells me "on" is a little better.

Just to reiterate though:

"On Christmas morning" is the most natural sounding.




think both are acceptable.

Thanks