Instead of trying to stem disappointment, it is far more instructive to teach your child that an external event does not have the capability of ruining his summer or his year. Rather, it is his response to the situation that counts. For example, you can explain that while he does not have control over the weather and its impact on an outdoor activity, he does have control over his response to the situation. Ask your child to suggest alternative plans and then encourage him to forget about what ‘could have been’ and focus his attention on making this a great day—regardless of the weather. As for the fear of having a bad teacher or a disappointing class—your child needs help to see that he will be able to get the most out of the class to which he is assigned, make new friends, and enjoy whatever his teacher has to offer. Every year I have students tell me they got the ‘worst’ teacher, only to find that by the end of the first semester they find this to be the ‘best’ teacher they have ever had. This isn’t usually because the teacher has drastically changed, but because the student’s (and parent’s) outlook is positive towards the teacher.
This philosophy can and should be applied to every disappointing situation. It is impossible to avoid the curveballs that life so often throws at us, so the sooner we learn to adapt, and make the best of it, the happier we will be. As a parent, it is your responsibility to give your child as much practice as possible perfecting this skill before she is too old to benefit from the lesson.