Unit 1 (We usually go to the park)
(How often) lesson 3+4
(Sometimes, usually, always and never ) are adverbs of frequency
We sometimes go to the park
She usually plays tennis.
They always paint pictures
I never play on the swings
We use how often to ask questions about frequency.
How often do you go to the park? I sometimes go to the park
How often does she play tennis? She usually plays tennis.