PHOENIX (3TV/CBS 5) -- The extreme heat sweeping through Arizona presents several challenges for Phoenix-area elementary schools.
Nobody was on the swings, or the slide, or the rock-climbing wall at Mercury Mine Elementary School in Phoenix Tuesday, which saw a record high for this date -- 113 degrees.
All physical education classes were held inside because of the extreme heat. Recess, too.
[WATCH: Keeping kids safe in extreme heat]
"When the announcement comes in, you hear it," said P.E. teacher Ean Urkew. "The whole class just erupts, 'Not again!' They want to be outside. You've got to make sure everybody stays safe, and use lessons that don't require a lot of space."
Excessive heat days like the one Tuesday (and forecast for Wednesday) take their toll on students and teachers.
[ARIZONA'S WEATHER AUTHORITY: Forecast]
Playgrounds are off-limits, with kids told to stay inside for lunch and recess.
Donna Alley, the principal at Mercury Mine Elementary, said most schools determine for themselves whether it's safe to let kids play outside, but when it gets this hot, they don't take any chances.
[SPECIAL SECTION: Extreme heat]
"Every child is different," said Alley. "You never know how much they've been hydrated or not, whether they've just been sick, whether their immune system is down. Some kids can handle the heat better than others."
Another reason students stay indoors on excessive heat days is how hot the playground equipment gets.
The swings on the playground at Mercury Mine reached 160 degrees.
The rock climbing wall was 179 degrees.
The slide was 198 degrees.
"When it's not overcast, and it's full sun, it's pretty treacherous," said Alley.
"We just tell them they live in the desert and it's hot out here," said Urkew. "We have to be smart and have to be safe. It's just part of living in Arizona."