Final answer:
The IV is the truancy prevention program and the DV is the number of truancies for each child. This is measured to determine the program's effectiveness.
Step-by-step explanation:
In the context of the school social worker's study on a truancy prevention program, the independent variable (IV) is the new truancy prevention program itself. This is because it is the variable that is being manipulated or changed to observe its effect on the students' truancy rates. In contrast, the dependent variable (DV) is the number of truancies recorded for each child over the nine-month period, measured at three-month intervals. The dependent variable is what is being measured or assessed to determine the impact of the independent variable.