Ashoe manufacturer wanted to determine which type of material, "material x" or "material y," to use on the soles of their shoes to get maximum wear. twenty teenage boys wore one shoe with each type of sole. for each young man, a coin was tossed; if heads, "material x" would go on the right shoe and "material y" on the left. if tails, "material x" would go on the left shoe and "material y" on the right. after wearing these shoes four months, the thickness of the sole of each shoe was measured. what type of study is this?

matched pairs experiment.

Explanation:

A matched pairs design is a specific type of randomized block design, that lessens variability from individual differences. It´s effective when the research has only two optional conditions, and subjects can be assorted into sets of two, with a blocking variable. Within each pair, the different materials are randomly distributed.  

This is a matched pairs experiment because there are two measures noted in each boy: the right sole is paired with the left one, so ware can be compared, but variations in wear from one boy to another is removed from the experimental error.

first of all, it's important to say that the book we shall not be moved, written by joan dash, is about the first strike of women in the united states in the year 1909. the best historical detail to clarify the reader's undertanding is the phrase "general strike". this strike involved women working at a garment factory who decided to protest   long working hours, low wages and brutal conditions. this strike became known as "the new york shirtwaist strike" or "the uprising of the 20,000". the strike mostly involved jewish women who did not speak english or who had a basic knowledge of the english language. finally, the strike went on from november 1909 until february 1910.