Here's a picture from Stewart's calculus for Simpson's rule
Since a parabola goes through $x_n, x_{n+1}, x_{n+2}$, we would get $\frac{n}{2}$ parabolas? So in this case of $n=6$, then we'd get $3$ parabolas?
So while I could make, say, 6 trapezoids for my approximation, I would only be able to do $3$ parabolas here?
The reason I ask is because I've been trying to find good applets to visualize the changes. A nice looking one is this one https://www.geogebra.org/m/RmKzByhq but the value of $n$ there seems different than the book's. It's probably due to how $n$ in the applet is how many sections the interval is made into, and so what is $n=6$ in the book is $n=3$ for the applet.
Yes, with $n=6$, you have 6 strips, and 7 points where the function is evaluated. Each parabola covers 2 strips, so there are 3 parabolas.