Schools are an expected part of communities. So a new school or replacement school would usually not impact values in any meaningful way - the exception being the properties that are on the same street as the school or back up to it. But the general community - if a school now or in the future impacts values, the sales would reflect it.
A comment, if you choose to make one: " A replacement school is being planned. Any impact on values is reflected in area sale prices." Neutral, yet true.
As an experienced appraiser, one learns that "anything you say can and will be used against you"... borrowing from the Miranda warning. If an appraiser makes a statement that the school will either positively or negatively affect value, then someone can challenge it - what facts support it? How did you arrive at that conclusion, etc. This can open the door to board complaints or a lawsuit. So unless the appraisal assignment is to specifically analyze the impact of the new school opening, keep comments about the school within the SOW of the appraisal.
If it were a prison being planned, or a big employer moving to an area, or a data center opening, etc., anything unusual might need a comment -but even there, it holds true that any effect on value is r will be reflected in sale prices and marketing times.