Flushed Face

• According to MayoClininc.com, most of the signs of heat exhaustion in kids will be physically apparent and easy to spot. The first and universal symptom of heat exhaustion in kids is a flushed face. The child's face might also be hot to the touch.
  
  

Other Symptoms

• Past the obvious warmth and redness of the face that will accompany heat exhaustion in kids, you may also look for some other tell-tale signs, such as sweating, dizziness, shortness of breath, a weak, rapid pulse, nausea and headache. If you notice a child with these symptoms, it is important for you to get her to seek shade, drink some water or lay down for a short period of time.
  
  

Fever

• If you have the chance, take the child's temperature. Those suffering from heat exhaustion may run a low-grade fever. You might also notice urine that is darkened in color, due to the dehydration a child suffers while experiencing heat exhaustion.
  
  

Physical Cues

• You should always watch a child's habits as he plays outdoors. He may slow down from playing spiritedly, or you may notice that he hasn't had anything to drink while playing outside. It is especially important to watch children in temperatures above 90 degrees, as these are the conditions that make kids more susceptible to heat exhaustion.
  
  

Risk Factors

• According to the Mayo Clinic, children are at a higher risk of heat exhaustion, due to an immature body temperature system, so make sure that you are vigilant in watching for the signs of heat exhaustion. Watch for overexertion on hot days, such as a lot of running, sweating and a redness in the face.