Pretty much every parent of a toddler has a story. A story of an epic meltdown that seemingly shows up out of nowhere but quickly escalates into sobbing, shouting, stomping and screaming. Sound familiar? Research shows that 87% of 18- to 24-month-olds have tantrums, and among 30- to 36-month-olds, that rate rises to 91%. Perhaps the only good thing about tantrums: They’re developmentally normal — and they provide a perfect opportunity to help children learn…