40% of teenage girls in western europe have at least one child before the age of 18. true or false.

Micah is studying child behavior in playgrounds throughout the world. he wants to see how the children react when teachers select the same child to be the first to use each piece of equipment. which approach is micah is using?

Which technological breakthrough of the 1950s revolutionized the way that americans kept up with news and world events? a) radio b) internet c) television d) motion pictures

Using mr smith and his id, identify two potential internal validity threats that might affect the a—b design. tell me how that threat might impact conclusions in the a—b design. note #1: you cannot use maturation (since i already did that one for note #2: there are some mr smith id threats that won’t have much impact in a single case design.