brighten up
phr. v..phr. v.. to become happier or to make a place look more cheerful and full of light.
phr. v.. to become or make more cheerful, lively, or luminous; can be used intransitively for mood/weather or transitively for physical spaces.
The sun is starting to brighten up the room.
She bought some colorful flowers to brighten up her new apartment after a long winter.
The atmosphere in the office began to brighten up significantly once the management announced the unexpected year-end bonuses.
often used with 'weather', 'mood', or 'rooms' as the subject or object.
use this to teach the suffix '-en' (bright to brighten) and how adding 'up' adds a sense of completion or improvement to the action.
The weather brightened.The weather brightened up.while 'brighten' is a word, 'brighten up' is the standard phrasal verb used for weather and mood improvements.