Just a quick note to parents out there: when someone says “3-year old” it refers to any individual who is from 3 years of age to 3 years and 364 days of age. It’s a categorical variable. The average “3-year old” is 3 years and 6 months of age. All of the measured “norms” of what a 3-year old can do is based on children who fall in that age range.
So if your 3-year old is one month away from his 4th birthday, it’s not OK to refer to him as a 4-year old just because he’s “almost 4.” He’s still closer in age to the average 3-year old than the average 4-year old, so you’re inadvertently comparing him to a group of children who are older than him, and you’re naturally going to feel like he’s falling behind.
In unrelated news, my 3-year old son is almost 4. 🙂