Which technique is used in the rating scale?

Compound among the following is 

Van Hiele's levels refers to stages in the development of? 

Which of the following features of mathematics makes it a global subject?

Select appropriate preposition to fill in the blank:
 They walked ........... the footpath until they came to a bridge.

Choose the correct option to fill the blank:
 Immediately after the operation he could see nothing_______ vague shadows.

Select the appropriate modal for the expression given:
 If you do that again you ______ be punished. (threat)

Problems of spelling errors of the students can be easily solved through-