Every test is formative.
I think I was in pre-algebra as a 13 year old version of myself, I was sitting at the dining room table, frustrated at the textbook flopped open in front of me resting on top of the macrame woven placemat. The book might as well have been in Greek, we were half way through the first semester and all the getting to know you, light weight, easy assignments had long since withered my early A in the class to a D that was a gift considering I now could not complete a single problem in chapter 6. Looking back, knowing now what I did not know then, I realize that I had holes in my learning: it wasn't that I couldn't comprehend pre-algebra, I was just trying to learn to use tools that I had never acquired, in an effort to accomplish a task that could only be perceived through a fluent understanding of the tools themselves. I was at a brick wall, a dead end, and all the help in the world could not move me forward - until I moved backwards.
My dad sat down next to me. I love my dad, and always have, but he was always more of a sock you in the arm and, "go get'em slugger," kind of dad. I was an young teenager and we had an unspoken agreement that I wouldn't tell him what I was doing as long as he didn't ask: it was a symbiotic relationship from which we both benefited. However, on this given day, in this given moment of frustration, my dad taught me something that has carried me for my entire life. He didn't try to push me forward. He didn't even try to help me with the homework that I clearly couldn't do. He did the unthinkable. He started turning textbook pages in the wrong direction. I didn't even know they could do that.
We went backwards, page by page, looking for the last place in the book where I felt confident. Granted, it was farther back than either of us had hoped, and to be honest, the story doesn't have a pot of gold at the end of the rainbow ending: I never did all that well in high school math. However, the lesson I learned that day made an impact.
I remember saying to my dad that day, something to the effect of this, "I guess it doesn't matter if I don't know something, I can always go back and learn it." While I remember my dad grimacing at the thought that I was ok with failure, I look back and think that this was my first introduction to a growth mindset.
Every test that I take just informs me what else there is to learn.