asÂ·soÂ·ciÂ·aÂ·tive property. The property of addition and multiplication which states that a difference in the grouping of numbers being added or multiplied will not change the result, as long as the order of the numbers stays the same. For example, 3 + (4 + 5) is equal to (3 + 4) + 5. See also commutative property, distributive property. 1  Facebook.
The most common recommendation is to initially place infants to sleep on their backs for the first 12 months. However, when the infant is able to roll over on their own in to the sleep position of his/her choice than it is fine to leave the baby in that position. My children are now 29, 27, 24, and 11.
To establish best sleeping practices long term, do try to put your baby down in his crib at bedtime, no matter what happens at naptime. 1. Put Him Down Earlier. Don't wait until your baby is beyond exhausted to put him down for a nap, or you'll risk him getting a second wind--or releasing the stress hormone cortisol, which will also keep him awake.