Fifth grade math

According to my fifth grade son, his teacher says they have to use a calculator in class to do fractions. The reason being that if they don't learn how to use a calculator, they'll get left behind by the other kids that are learning to use them. My question: How long does it take to learn that to add, you push the "+" button... to multiply, you push the "X" button... I'm also wondering when they're going to be teaching him how to convert back to a fraction from a decimal answer.