Alarm is signed by holding your non-dominant hand open, with your forearm upright, as if to suggest the face of a clock or alarm bell. Then you take your dominant hand in a first, with thumb and index finger both pointing up. The dominant hand strikes the non-dominant hand several times.
Alarm looks like the opposite of bell, where the pointer finger is facing downward, as the clapper or tongue of a bell usually does, whereas with alarm, the pointer finger or "clapper" is facing up.
Teach your child the alarm sign in the context of a real-life situation or when seeing it on video or television. It is useful to teach this sign to toddlers particularly in an emergency situation, where they need to be alert and stick close to Mommy or Daddy.
Teach your child the alarm sign when they hear an alarm clock at home, when they hear the alarm bell in school, or in the context of a hospital, police, or fire station emergency.