It does depend on what your HT means by Success Criteria. This term can cover process steps when working through different methods.
For example, to find a non-unit fraction of an amount e.g. 3/8 of 400
Success Criteria (process steps)
1) Draw a bar model to show the whole - in this case 400
2) Use the denominator to split this bar into equal sizes to show what the whole is divided into (divide into 8)
3) Work out the whole divided by this denominator to work out each part (in this case an eighth)
4) Look back at the question - we were asked for 3/8 - so we need 3 of these parts..
This might not be what you were meaning at all - but I have come across different folk who use terms where different interpretations can take place!