Regarding first question,the teacher was having them use a number line,counting from the 10to 30 then count how many marks they had,then add the number of marks to 10 to get 30.They never subtracted.This seemed like a harder way to get the ansewer.
Unfortunately, most schools these days have a specific math program that they have to teach by. I agree it is often a strange and complicated way of answering an otherwise simple math problem. And the kids become very frustrated when we try to show them "our easier way". They're simply required to answer their math problems the way the teacher presents it to them. I believe all schools now have a website where you can learn about their math program. This will help you to help your granddaughter. Good luck!