Rough start at preschool

We've had a rough start at the new preschool.  The first two days the report on Emmy has been that there are examples of times where she has thrown some fits about not getting her way.  Bobby on the other hand has been an angel!   Robb and I have had many discussion with Emmy about how she needs to behave at her new school but really feel she is testing her limits there as she is such a good girl at home.  Yesterday on the way home I gave Bobby and reward snack for his good report and could not give Emmy one since she got a bad report.  She cried and I had to try so hard not to cry too!  Parenting is really hard when it comes to disciplining your kids and I know it doesn't get easier.  I hope she start to adjust to all of the new rules and restrictions with the structured schedule of preschool.  We are not paying big bucks to have her go to this school where she has class every day and I just want my kids to be happy so I can feel content to work all day.