In 1950, how many cities had a population greater than ten million, worldwide?

Television programs with __________ are associated with improved executive function, greater recall of program content, gains in vocabulary and reading skills, and more elaborate make-believe play

A) action-packed storytelling B) quick, disconnected bits of information C) slow-paced and easy-to-follow narratives D) a spoken summary of the lessons learned at the end

Ensuring that all variables are constant in an experiment, except for the independent variable, is called

a. random sampling. b. experimental control. c. random assignment. d. experimental manipulation.