This paper examined the effect of the Unplugged Programming Teaching Aids (UPTA) on students' computational thinking and classroom interaction. A set of UPTA was created and used in a primary school in southern China. A total of 48 students aged 6-8 were assigned to two classes, with the same instructor and learning materials, but only the treatment group was provided with the UPTA. Both groups were tested on computational thinking ability, children's concrete operation status, degree of ego-centricity, and in-classroom interaction. Results indicated that the children aged 6-8 years old could classify things according to two kinds of criteria at the same time, but their cognitive style was still ego-centered and they found it difficult to deal with problems from a third-party perspective, no matter whether in the treatment group or the control group. However, students in the treatment group achieved significantly higher scores on the test of computational thinking and were more engaged in the classroom interaction patterns. These findings provide evidence of the positive effect of the UPTA on promoting children's computational thinking by guiding them to decompose and solve problems, as well as enhancing their interaction and communication in the classroom, so as to transform from simple imitation to collaborative inquiry.