How to Tell if Your Toddler is Smart - Look for the early development of language skills. Children are expected to have a few words by 15 months old, for instance, but if they are stringing together two-word sentences they are likely ahead of the curve. -Observe gross motor skills, like walking up and down steps. Can they alternate feet when they walk up and down steps? - And then tell them a dad joke, such as: Why do seagulls live by the sea? Because if they lived by the bay, they'd be bagels.