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.
Your baby needs about three hours of sleep in the day until he's around nine months. Most babies have a longer nap in the morning and a shorter one in the afternoon. Between nine months and 12 months, your baby's naps will reduce to about two and a half hours in total a day. If you'd like your baby to have a bedtime of 7pm, try to make sure that he doesn't take a nap after 3pm, as this may disrupt his bedtime routine.