In my experience the measuring is not consistant. My youngest dd measured 41" barefoot at the doctors about a month before our trip 2 years ago. At BTMR she hit the stick no question, no hat, no high shoes, she loved it. Next door at Spash Mtn - same 40" requirement - again no problem loved it. WE got a FP for Splash and went back and rode BTMR again When we returned to ride Splash low & behold she was an inch short! Long story short watch out for the uneven ground here. We had her re-measured on flat ground and she was indeed more than tall enough. They will also measure "questionable" children a few times - my dd' loved the challenge LOL.
We did try for dinasour at AK that same trip - same 40" requirement but she was well short both times???
I was aware that she may not hit the stick and we were all prepared for the result of the "measuring" but the inconsistancy should be delt with.
Fast forward to last December when the same dd was just 44", she had been waiting to "measure up" for Space Mountain. I was sure she was not tall enough and did not even want to try. DD went marching to the CM and asked "please measure me, I am tall enough for this ride now!" and sure enough she was. No question, the stick was about an inch shorter than dd's head, no hat no big shoes. DD loved this ride and we rode a couple times that day and the next.
Then at
MVMCP she entered the line, got measured and was at least 2" shorter than the stick! (same shoes) We were both stunned and the CM had evidently "heard it before", (can't say I blame him as he surely has). DD politely said "I was tall enough yesterday" and he very sarcasticly told her "you must have shrunk". MY dd repled "kids don't shrink" and we left. DD was disapointed while I was left questioning letting her ride the day before. Had I put her in danger, was the stick the wrong one etc.
End of story was that for the remaining several days of the trip she was indeed tall enough to ride and our incident at MVMCP was some fluke. So - its a human thing and errors will occur. You and your child will have to accpet the ruling of the CM on that particular day. Unfortunately he may be able to ride one day and not the next :-(.
It would be nice if they would start measuring at the entrance or some other "central" point like some parks do. Our local park has a wristband system so you know at the start of the day what you can and can not ride. I think it would make it easier on the cast members to.
If there is something your child really wants to ride be sure and pepare them . Explain the rules and why they are enforced, have a back up plan and make it exciting. If we can't ride BTMR this time we can do ______ instead. Talk about it ahead of time and find out what he/she would like to do if you can't ride. You may be surprised when they ask for ice cream or the spinny toy you would probably buy anyway!!
Some CM's will pass out a FOTL pass for kids to use on the return trip when they are tall enough.
TJ
. Some of the rides they let him on, some they didn't. I think it depends on how much you stretch them when they are being measured 
