Final answer:
The study described by the student is an example of longitudinal research, as it follows the same group of children over an extended period of time to observe the impact of pre-schooling on educational success.
Step-by-step explanation:
Studying a group of children from first grade through high school to see the effect of pre-schooling on educational success would be longitudinal research. This type of study involves following a group of research participants for an extended period of time. It is a research design in which data-gathering is administered repeatedly over an extended period of time to observe changes or development in the research subjects.
A cross-sectional study, on the other hand, is an observational study that collects data from a sample of subjects just once at a certain point in time. Observational studies measure characteristics in a sample but do not attempt to manipulate variables of interest, as opposed to experimental studies which do involve manipulation and control of variables.
Therefore, the correct answer to the student's question is B. longitudinal research, which allows researchers to track changes over time and is particularly useful in developmental and educational studies.