I remember elementary school. It was an easy, somewhat boring place where everyone walked to lunch in nice, neat, perfect straight lines and you would be fine as long as you knew your ABC's and could add two and two. After six years of enduring that, you are suddenly thrown in middle school: an unforgiving, terrifying, academically reputable madhouse where you need to write essays and solve intricate algebraic expressions. Obviously, these places have many noticeable differences, even at first glance. In my opinion, the most noticeable of differences between the "every student for themselves" attitude of middle school, and the "everything is sunshine and lollipops" elementary school is the fact that we switch classes.
For one thing, instead of having one class for the entire day, you have seven. That's seven teacher's names to learn at the beginning of the year, seven different homework assignments for one night, seven different subjects to learn, seven different tests to study for at one time, need I go on? Compared to the 'One teacher per year, one homework assignment per night, and one test every week' philosophy of elementary school, that alone is a lot to get used to in very little time.
As if that wasn't enough, I still haven't gotten to the most important part of this commute between classes: actually getting there. In elementary school, you always walked to lunch in perfect lines. You had your line leader in front, your caboose in back, and you were playing the quiet game. It was tedious and especially frustrating when the line leader was walking slower than molasses with everyone behind trudging along behind them, or speeding down the hallway like an Indie 500 racer, with everyone struggling to keep up.
Then you get to middle school. This is completely different than anything your elementary school teachers ever taught you about walking in hallways. In middle school, you're thrown in there, with five minutes to get halfway across the entire enormous school, when everyone is walking the opposite direction than you; shoving and pushing, and yelling "get out of my way!", right in your face.
The changes from elementary to middle school are drastic. Boring repetition and walking in straight, quiet lines is no longer in question. Despite the initial chaos, these sudden changes are actually new freedoms and responsibilities. It just depends on how you look at it.