I'm thinking of blackmailing my teacher
What do you need to blackmail them for?
Because I want to get a higher grade
Wanting to get a better grade is commendable but you should be putting in the work for it. Blackmailing people is extremely wrong and you're likely going to get yourself into trouble doing that. Just study hard complete your work and you'll get a good grade on your own.
I will get this a my way... I don't care if I just got myself into trouble.
Blackmailing someone is not a good route to take. You should try your best and then see what grade you get without being spiteful. I bet you can get at least a B.