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.
Eventually, after two weeks to 1-2 months, your baby should start to accept the idea of falling asleep outside of your arms and should be able to put himself to sleep. More traditional sleep training looks like the Interval Method, which involves putting your child to bed drowsy and coming in at set intervals (letting him cry it out for 5, 10, 15 minutes, etc.) and staying in the room for one minute, patting your child on the back, but not picking him up.