Final answer:
The constant in the textbook experiment is B) The middle school students, as this group does not change during the experiment while other factors like textbook type and exam grades do.
Thus the corret opction is:d
Step-by-step explanation:
In the experiment where students were split into two groups and received different textbooks for their science class, the constant would be the variable that does not change throughout the experiment.
In this case, choice B) The middle school students can be considered the constant because the composition of the student body remains the same irrespective of the type of textbook they received.
The type of textbook (A) is the independent variable, the final exam grades (C) are the dependent variable, and the school year (D) could vary or remain the same but is not related to the experiment parameters directly.
The complete question is:content loaded
Which of the following is a constant in the experiment where students were split into two groups and received different textbooks for their science class?
A) The type of textbook received
B) The middle school students
C) The final exam grades
D) The school year