Over the last couple of weeks, my research team and I have been collecting data on relational aggression with two different age groups: 5th-graders and 7th-graders. It has been an incredible experience and we are so grateful to the school staff, parents, and children who are making this research possible.

Something that several of us on the research team keep coming back to is what a very big difference a couple of years make. Two years and a school transition separate the two grades, but as any parent of adolescents can probably tell you, those two years might as well be twenty.

Our 5th-grade participants were still all about ME. They were impulsive, excitable, and quick to smile. It took many of them several minutes to choose a piece of candy from our “Thank You” grab bag; they had to dig through the entire thing to make sure they were choosing the very best piece of candy in the bag. (This drove their peers bananas, but the very children demanding “Hurry up!” were the same ones spending endless minutes choosing their own candy when their turns came.) They asked questions about the research we were conducting and seemed genuinely interested in the answers. Perhaps most endearingly, many of these kids seemed to enjoy our visits (we were in their classrooms, briefly, every day for a week). I saw smiling faces call out greetings to my research assistants in the hallways, and although the greetings usually went something like “Hey, do we get candy again today?” I could tell that the smiles were about more than candy.

Our 7th-graders were a different bunch. They were more suspicious of our intentions, but they didn’t seem to ask as many questions as their younger peers did. (Maybe being curious isn’t cool.) One boy asked me if participating in the study could affect his chances of getting into college later on; it was an easy question to answer, but I wanted to give him a hug along with my reassurances. 7th-graders were way more concerned about how their actions were seen by their peers. No more taking forever to choose a piece of candy; they looked quickly and grabbed what they could see in a second or two, and we heard “Hey, don’t be like that” from kids when their peers took too long to choose. Thirteen-year-olds keep each other in line in interesting ways. And they weren’t as positive about our visits, at least not openly, but they took our surveys seriously and seemed to have an appreciation for what we are trying to do: Understand them.

So what’s going on in those intervening years that changes kids so dramatically—why do they move from being happy-go-lucky to being more cautious, more reserved? We know that the middle school transition is a tough one for kids. We ask children to move from more personal, more intimate classroom relationships with a small group of peers and one teacher to the much larger social world of the middle school, where they have several teachers and interact with many peers over the course of a day. It must feel overwhelming and impersonal, and at a time when kids need to feel connected to trusted adults, they may not feel like they have opportunities to create those relationships. Research by Jacqueline Eccles and her colleagues has documented other differences between elementary schools and middle schools that may be causing trouble. For example, they argue that just as adolescents are craving more autonomy, they enter schools with more rigid, authoritarian approaches to discipline and order. Just when they crave closer relationships with peers, they find themselves among sometimes hundreds of peers, trying to figure out who they fit in with and who they can trust. Social comparison increases, and kids are concerned about how they look to others (and become depressed when they find themselves lacking.) It’s a recipe for trouble, and when I think of my young participants, some about to make the transition and some who have already done it, I’m proud and impressed that most of them manage to handle it so well.