If you wanted to examine whether attitudes toward learning differ based on students' grade in school (i.e. ,first,second,third) ,what is the independent variable of interest?

A) grade level
B) students' attitudes
C) parents' attitudes
D) level of parent involvement

The independent variable of interest is the variable that is being manipulated by the researcher to see if it affects the dependent variable (attitudes toward learning). In this case, the independent variable is the grade level of the students, as the researcher is interested in seeing if attitudes toward learning differ based on whether a student is in first, second, or third grade.