An example for the columbian exchange

Below is a description of a resource that you're considering using for a research paper. as you read the description, keep in mind what you've learned about historical thinking skills and use those skills in evaluating whether or not to use the source.

The process of rocks breaking down and becoming other rocks

Pj conducts an experimental study on the effects of soft music during high stakes science testing. he randomly assigns students at the school. in one condition he does not provide music for testing while in the other group he does provide the music. he administers a pretest at the beginning of the year and a posttest at the end of the year. pj’s design is best described as a: a.static group comparisonb. pretest-posttest control group designc.control-group-time-series designd. nonrandomized control-group pretest-posttest design