Extravehicular Activity (EVA)

VISUAL 13 (movie): EVA
Astronauts also go outside the Space Shuttle to do work. When they do this, they must wear special space suits. There are two reasons why. 

Who can tell me what they are?

[So they can breathe and so they can stay at the right temperature.]

These space suits have heating and cooling systems and air tanks, since there is no air in space and it can be very very cold or very very hot. This astronaut is testing out a special wrench that was designed to solve a problem about turning screws under weightless conditions. You see, with an ordinary wrench, if an astronaut tried to turn a screw under weightless conditions, the astronaut would turn, not the screw!

Fade off EVA sequence.