Educational psychologists investigate the impact of different types of instruction on learning. In one study, researchers taught a math lesson to 9th-graders using the "Inventing to Prepare for Learning (IPL)" instructional cycle. A second group of students received traditional "tell and practice" instruction. After the lessons, both groups studied a worked example of a math problem on their own. Then they took a test that included problems like the worked example. The journal Cognition and Instruction published the results in 2004. Pick the best description of this study:

(A) an observational study of an association between two variables
(B) an experiment to establish a cause-and-effect relationship between two variables
(C) No answer text provided.
(D) an observational study to make an estimate or a claim about a population

new communications technology has affected the way social movements are organized because nowadays, social movements rely on social networks and the media to get different people with a similar way of thinking in contact, and thus, get them to mobilize for a greater cause.

individuals only participate in collective action when they feel identified with it. is in this aspect that social media becomes relevant, because it guarantees communication among all individuals and organizes the social actions that are going to be carried out, i.e., the social movements.

in addition, being covered by the media is important to validate the message and make it relevant in the social agenda, as well as to reach more people who can share interests, appealing to public sympathy for their cause.

in conclusion, it is by social networks and social media that social movement is given birth; by connecting different individuals with similar ideas and organizing them to mobilize for a greater cause.

hygrometers and hair thermometers (often found as part of hygrometers/psychrometers) can be used to measure humidity. barometers are used to measure atmospheric pressure, while anemometers are used to measure wind speed. so the 2nd and 4th choices should be the correct answers.