around 7 months

Your baby is beginning to understand a lot about how things work in the world. One example is "object permanence" — understanding that an object continues to exist even after it disappears from sight. That's why peek a boo is a favorite game. Similarly, if your baby drops a toy or his dummy out of his crib or highchair, he may look for it, whereas in the past he cried for the object because it had gone missing.

jack in the box would be fun right now!