Poner nota a alguien en un examen oral/escrito
 

How can I say? poner nota a alguien en un examen.
Yo le pondría un 8.
tenemos diferentes criterios para poner las notas.

I would give him 8 marks??
We usually have different criteria at the time of giving marks ????

In this case you will need to clarify what you mean. If marks are negative, you would say, on his exam he has 8 marks against him. You can say, he has consistently gotten good marks (or grades) on his tests.

I believe "Put a mark on an exam" would make sense in British English.

In American English: 'Grade a test.' or, less common, 'Give/Assign a grade for/to a test.'
"I'd give it (the test) an 8, or a score of 8."

A score of 8 wouldn't make sense in America. We assign a score of 100, or a letter grade of 'A,' when someone gets every response right, and subtract points from that perfect score for each incorrect answer given (or a percentage is calculated). The score/percentage roughly corresponds to a letter grade. One college posts their grading criteria as documented in the table below.

Percent	Letter Grade
94-100	A
90-93	A-
87-89	B+
83-86	B
80-82	B-
77-79	C+
73-76	C
70-72	C-
67-69	D+
63-66	D
60-62	D-
<60	F

your are giving an oral test and you need to mark then (ponerles nota a los alumnos) I thought it was to give them a mark

o que nota me han puesto?
what mark did you give me?

In America, a teacher "grades (the) students" or "gives students a grade," based on how well they did on a test (oral or written). We don't use the word "mark."

I'm not sure what they would say in the UK, but "gives students a mark" sounds reasonable.

In US teachers mark (or grade) tests or papers. A student who receives good marks is doing well.