Strumming is to scratch or brush the strings as blocks. We could call it a ‘whap’. When strumming, we don’t drag the pick or finger through the strings, rather, we give them a good whap [hit them as a ‘block’]. We can drag through the strings, & this is called a rake or a drag.
The primary motion for strumming is ‘key-turning’, with the elbow giving it weight, with a ‘chop’.
Our stated rule for strumming is that at the beginning, while training, the strumming hand never stops moving down-up – whether you are hitting or missing. At the start, log a lot of time strumming down-up while hitting on both the down & the up. This will lead to strumming and changing chords being relatively simple.
Becoming a reliable rhythm player is base level for becoming a guitarist. To do this, we train our strumming while synchronizing events to it [chords, types of touches]. We can evolve our strumming quickly by exploring the different facets of our overall strumming system.
And, rather than learning ‘strumming patterns’, we develop our rhythmic abilities by considering (training) different facets of the the overall strumming system.
The overall rhythmic sound shape from strumming includes combinations and mixing these things together: Hitting/Missing, Range, Dynamics [volume], Accents, Tempo, Double-timing and Touching [Muting]-Pressing.
We can’t possibly micro-manage all of these facets. Our goal is develop our rhythmic self and skills by training in intelligent ways. Read more about ‘strumming patterns’.