The digital content has been considered as a core part of classroom learning. The way to input answers may influence student learning behaviors. This paper focuses on three computer-based input types - choice buttons, drag-and-drop, and text boxes - that are used frequently in arithmetical word problems of elementary schools. The experiment was conducted to examine how students input answers in computers and how they are engaged in learning. The results showed that the students had high accuracy when they had to type their answers; they were willing to spend time on studying the questions and creating the answers. When students were allowed to choosing or dragging-and-dropping, some of students would guess the answer by the "advantage" of computers - instant feedbacks. This paper suggests that the interface should facilitate a student to be a hard worker rather than an opportunist.