I've been thinking a lot about this family tree/family heritage assignment. As I do, I've thought of a few positive things about it, especially coming at this age, and for this kid.
When our son was in 3rd grade and having similar assignments, he'd just been with us a year. He is also much more reluctant to talk about his past, and has a lot more trouble expressing his emotions, much less analyzing them. So with him, we simply let him do a timeline of the one year he'd been with us for the timeline project, and put together a rudimentary tree of our family without any in depth analysis.
Our daughter is starting her 4th year with us, and has always been more equipped to analyze herself and her feelings about her past. For Linden, I think we will be able to use this assignment as a way to open up some conversations. If we do the root-and-branches adaptation of a family tree, we will still have very little information about her "roots," but we can put in what we know, and talk a bit about the grandfather they lived with when they were babies as well as siblings. We can talk about the mystery of birth dads and some more about the life of their birth mom. This will be a great reason to pull out their books of photos of their birth certificates, hometown, and orphanage, and for me to pull down the further documentation I have stashed in the closet and let them look through it.
They have a sister living in their home country, whom we have had very little contact with, but whom Linden thinks about and talks about from time to time. This assignment will give me a kick in the rear to reach out to her and her family again, to try to build a bond between the siblings.
We are fortunate in that my grandfather was from my kids' country. (Well, it's not a coincidence, and was also an asset in the adoption process.) So the assignment that involves researching your ancestors' culture will work both in a bio- and adopted- family way. We can share the research, as is the intention. I sometimes wonder if my kids and I are distantly related by blood--it's a small country, so it's possible, if unlikely. My kids recently worked out that the fact that their dad is a descendent of Ben Franklin does not make them descendents of him, which was disappointing. Maybe knowing that their cultural history matches mine will help them feel connected in some way.
I'm hopeful that Oak will also get interested in what we're doing and talking about. Having it be his sister's assignment might actually make it easier for him to express interest. I'm picturing family conversations that grow naturally out of our exploration of the past. We do bring all of this up periodically, but the structure and depth of the assignment might be a good tool for extending our conversations and giving the kids information appropriate to their current stages of development.