Parents shouldn't ask a child how he feels before school unless they notice signs that may indicate an illness, such as looking pale or flushed, swollen eyes, etc. Some 5 year-olds may not be ready for kindergarten. Many teachers report they see the most learning problems with the youngest children in their class. As a result, they may begin to feel badly about themselves. Holding a child back is better than setting her up for failure.
Many schools offer pre-kindergarten screening using scientific methods.
If the school doesn't, then ask for a referral to a testing agency. A physician can also assess a child's physical and developmental readiness.