Anne's study compared pre-post differences in prekindergarten children's strategies for alternatives to violent displays when frustrated by others. She found that there were differences between pre and posttesting. With which validity threat should Anne be most concerned?

What was different about warfare in the early 1800s and early 1900s?

Which of the following selections is least useful for supporting the claim that states intentionally built unequal school systems? question 1 options: the supreme court ruling in plessy v. ferguson (1896) wrote into law that america had two separate societies: one black and one white. it was very clear by the mid-1900s that southern states had expertly built separate educational systems. these schools, however, were never equal. states with laws keeping schools segregated never gave equal amounts of money to their black and white schools. ten years after brown, fewer than 10 percent of southern public schools had integrated. some areas did not comply at all.

The physical feature that makes up part of the border between canada and the united states is the