Breakdown of Esta aula está muy fría por la mañana.
muy
very
estar
to be (location/state)
frío
cold
por
for / by / through / in (during a part of the day)
Questions & Answers about Esta aula está muy fría por la mañana.
Why do we use Esta aula when we normally say el aula?
The word aula (classroom) is actually feminine. It takes the masculine article el (el aula) only because it starts with a stressed A-sound, which avoids the awkward sound of la aula. However, this rule only applies to the articles el and un. For demonstrative words like this or that, we stick to the feminine form: esta aula.
Why is the adjective fría used instead of frío?
Because aula is a feminine noun, any adjectives that describe it must also be feminine. That is why we use fría to match the feminine gender of the room, even though you are used to seeing it with the masculine article el.
Why use está instead of hace for cold? Don't we say hace frío?
Why does the sentence use por la mañana instead of en la mañana?