Answer:
observer effect
Explanation:
Based on the information provided within the question it seems that the problem that is affecting this quasi-experiment is the observer effect. In the context of psychology this term refers to a theory stating that observing a phenomenon or experiment may change the results. Which is what is happening in this situation since Dana's presence alone seems to causing the children to not do what they normally do. Thus affecting the experiment.
Answer:
yes
Explanation:
if the upper group agreed
In the Mexican-American war, the Mexican's were not prepared for the battle: they did not have a strong enough army to handle America and they were already falling apart.
Source was History.com if you need more
Answer:The population was becoming too old
Explanation:
670,2600,66,700 that should be it because b.c is before Christ and a.d is after death