The reason for flushing the toilet between children is because when the next one goes they splash up the germs in the previous pee. Now having said that too bad - we all go and I flush when we are done. More so that flushing is a time waster and the next one doesn't want to sit as long as the water is running so takes too long for potty breaks if the whole group is doing it. That is likely where mom is coming from. Which is fine but brings it back to not flushing unless they do a full pee and not just a piddle.