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.
The American Academy of Pediatrics recommends placing babies on their back to sleep, tummy to play.. Here are some ways to encourage tummy time. BIRTH TO 3 MONTHS Soothe baby on your lap: Instead of holding or burping the baby while he is upright, facing your shoulder, place him face-down across your lap. Put a hand on the baby's bottom to steady and calm him. While you're on the floor or bed, lie back and place your baby on your chest or tummy, so that you're face-to-face. Hold him firmly to keep him from rolling off. Spend time eye-to-eye with the baby, such as when you're both on the floor or bed.