Part 1
http://kazakhstan.adoptionblogs.com/weblogs/how-to-talk-to-young-children-about-adop

Part 2 - shared with permission

Let's look now at where your child is likely to be at age six to seven. At about this age, a child's cognitive ability will take him beyond the concrete, to think beyond the information and opinions that his parents have shared with him regarding how they feel about adoption and having brought him into their family. He is having more and more contact with the outside world and is becoming increasingly aware of the negative misconceptions our society has about adoption, racism, and the intrusiveness of strangers with adoptive families, as well as his parent's pride in having adopted him into the family. The six or seven year old continues to be interested in what his parents have to say, but is more and more drawn to the opinions of his peers. He no longer shares all that he thinks, feels, or knows with his parents, preferring to keep secret some of his inner thoughts. What he is confused, sad, or embarrassed about he is likely to keep to himself. If parents are going to get beyond the facade of "I don't EVER think about adoption" they are going to have to learn to tune-in to their child's round-about way of sending clues and also his behavioral clues that will signal that he is thinking about adoption and how it pertains to him.

The six to seven year-old, for the first time, is really able to understand that adoption involved a loss as well as a gain. He is able to think about, wonder about and have intense feelings about the birth parents who made an adoption decision for him. His feelings range from sad to angry and he may engage in lots of fantasy about who they were, what they were like, and why they couldn't "keep him." For the first time, he is having to respond to questions regarding why he was adopted with his peers-- without the help of his parents or another adult, as these types of questions usually are asked at the bus stop, in the cafeteria, or on the playground when adults are scarce. Often, it is an older child who is asking these questions. When he behaves in ways that get him into trouble with his parents, he may worry that they, too, will decide not to keep him, for he couldn't possibly understand enough about adult problems that would lead a set of birth parents to make an adoption plan. Fearful even of hinting about this, he worries in silence. Still having a short attention span, he does not dwell on adoption questions and feelings, but jumps from these concerns of the moment to what he is going to have for a snack, who is having the next birthday party, and who he is going to play with this afternoon.