Chiaki seems to be able to jump very high when she wants to, as evidenced by the last page.
Atsuko is in the category of "which character is that again?" for me. When it comes to Haruka's classmates, I remember Hosaka and Hayami plus Natsuki from the other Minami family and that's basically it. At least this is the sort of manga that has character names come up in dialogue very often.