As 3-year-old Angelo eats his bagel, he accidentally breaks it in half. He then says to his mom, "Uh oh, the bagel gone. I go get another." Angelo is in the _____ stage of cognitive development

An example of stage-three behavior is

thumb-sucking and self-soothing. searching for a teddy bear hidden under a blanket. trying to dress like Mommy or Daddy. looking for a smile and smiling back.

Ideally, everything in an experiment except the independent variable is held constant

Indicate whether this statement is true or false.