In order to measure aggressiveness in toddlers, a researcher sat on a park bench for an afternoon and observed children playing on the slides and climbing equipment. to get clean results, it was very important that the toddlers not know that someone was observing them. what type of experiment would best fit these criteria?

The answer is a Natural Experiment.

A natural experiment takes place in natural settings and are used when independent variables can't be manipulated directly for ethical/practical reasons, so in this case the toddlers playing.  Any effect observed happens naturally. They aren't seen as true experiments as the independent variable (toddlers playing) hasn't been changed deliberately to see effect on dependent variable (aggressiveness).

cannabis

explanation:

(assuming this is the us) google it. law states you can't have weed.

the arab empire adopted the muslim religion as their main belief. arabs would influence the people from the territories they invaded towards islam (the muslim belief).

nevertheless, throughout the history of the arab empire, rulers brought intellectual individuals from other religions to their centers of learning. these other foreigners included jews, christians, greeks, persians, and indians.   these resulted in the adoption of important knowledge developed by these cultures by the arabic empire. for example, the works of aristotle were translated from greek to arab and indian scientists brought the numerical concept of "zero" to the arabs.

nowadays, 93% of the arab population is muslim, which at the same time is subdivided in sects including the sunni, zaini, alawi, shia. the remaining 7% is composed mainly of christians.