To assist self-study of C programming through code reading, we have proposed the grammar-concept understanding problem (GUP) and the value trace problem (VTP). A GUP instance asks the keyword in a given source code that corresponds to the grammar concept described in the question. A VTP instance asks the value of an important variable or message in the code. In both ones, the correctness of any answer is marked through string matching with the correct one. In this paper, we present the application of GUP and VTP instances to first-year undergraduate students taking a C programming course in the computer science department at College of Engineering, Nihon University. The same instances are assigned to be solved several times during the course. The results observe the progress of the correct answer rate as the course elapsed and confirm the effectiveness in study by novice students.