Don't worry in practical if you perform good then you will definitely score 27 or more  every teacher want a good result from their students so they will not deliberately provide you less marks until or unless you don't make a mistake in practical

Heyy Ria....

If this is the case, then you'll have to be more careful that you don't give your teacher any chance of complain against you while in the practical exam or any such opportunity where she can deduct your marks. Know your practicals thoroughly and you should be able to perform them exceptionally well with accurate readings.