Hi Michele,
The ability to ride the attractions at Disney World is determined by height, not age.
On this link
HERE , look on the left hand side. Click on the "height' box and select your child's height,
it will help you determine which attractions are appropriate for your child.
In addition, if you look at this page of travel tips for people with small children found
HERE,
you
will see a button on the right hand side of the page that says
"Attraction Height Requirements." Clicking on this link will bring you to handy
PDF that you can download. The PDF lists the attractions in all four
theme parks and both water parks that have height requirements. If an
attraction is not listed on this document it means that there is no
height requirement and any size child can enjoy the ride. In addition, the height
requirements are also listed on all the maps at the parks and on
signage in front of the various attractions.
Hope this helps and have a wonderful vacation,
Kaylene