Present simpleGrandma drinks tea in the morning.
habit / routine / fact / preferences
SHIT-rule (= he/she/it + verb+s)
use do/don't or does/doesn't
Present continuousGrandma is drinking tea right now.
Happening right now, future plans, annoying habits
am/is/are + verb+ing
am/is/are + not - swap subject and verb in the sentence