7.1 (second half), due on March 7

It's cool that we can define groups using geometry transformations (that isn't something I would have thought of).  It's also cool that a ring with identity ALWAYS has at least one subset that is a group under multiplication. The hardest part to wrap my mind around  was the last example because they defined the cartesian product of real numbers and D4. Since I can't visualize this, it was hard for me to think about as a group.