@sait2009 The very first line of this page reads "アメリカ やばくない!?" that I translated as "America!! Isn't it terrific?". In English "terrific" means literally something that terrifies you, but often refers to something awesome. Likewise, in Japanese, you can say "この本、やばくない!?" which is literally negative, but actually used in a positive manner. Hence my choice of "terrific" to carry this dual usage*. My point is, the kids are not really scared, they're excited. That's something that happens in other mangas like Gantz from the same mangaka, people tend to be depicted as total selfish morons. So the tears and the shivers are not to be taken too literally. Look at the girl next to the bubble, and the overall relaxed mood in the classroom.
* I now have a very good example of what I was thinking about but it's actually a bit different. In chapter 51, page 6, Chiho asks about how bad it is in the US: アメリカ, 凄いことになってる? Then page 11 Rei looks at the stars and says: 凄げえ. The same 凄 used differently within the same chapter.