does teacher to student ratio matter that much for CCs ? realise that most hdb cc max out the ratio which means each kid gets less attention :( will it affect their mental and emotional development?will they be less expressive as a result?

Teacher to student ratio is for us to note that should anything happened, one teacher should be able to take note. The ratio is given as a guideline. If you are truly concern about the ratio, option is to go private school but the ratio may not be any better as preschool these days are pretty much maxed out and placed on waiting list. You can send your child for enrichment classes ie speech and drama class. Otherwise the maxed out ratio shouldn't be a problem unless the child already has pre-existing condition.