## 2 Hypothesis Development  
Research on the influencing factors of teachers' intentions to implement STEM education has some problems, such as small sample sizes, being limited to teachers of a single subject, and the need for optimization of the theoretical model relied on [22,23]. To predict an individual's behavioral intentions, a series of models have been constructed and adopted. Among them, the more impactful models include: the technology acceptance model (TAM) [24], the theory of planned behavior (TPB) [15], and the decomposed theory of planned behavior (DTPB) [25]. The DTPB was put forward by [PERSON] and [PERSON] after they compared TAM theory and the TPB. In the DTPB, attitudes, subjective norms, and perceived behavioral control, the three influencing factors of the TPB, are decomposed into lower-level belief structures.  
Attitudes include perceived usefulness, ease of use, and compatibility. Subjective norms include peer influence and superior influence. Perceived behavioral control includes self-efficacy, resource-facilitating conditions, and technology-facilitating conditions. The DTPB model and other models have been verified and compared in different fields, proving that the DTPB has more accurate predictions and explanatory ability by adding decomposed variables [26; 27]. This model has been widely used in research on, for example, the intentions of pre-service teachers to use Web 2.0 tools [28; 29] and implement ICT [30], and the intentions of junior high school teachers to use online learning platforms [31]. Therefore, this research selected the DTPB model as the basic theoretical framework to comprehensively forecast and interpret the influencing factors of the intention to implement STEM education by Chinese K12 teachers.  
Readiness is the level of ability and willingness shown by an individual in a particular job [32]. The readiness of a teacher has a great impact on the quality of classroom instruction, the effectiveness of classroom instruction, and the acquisition of students' abilities [33]. [PERSON], [PERSON] et al. [34] found that teachers who had more knowledge and better attitudes toward STEM education were better prepared for STEM education.  
As a result, this research proposes that readiness should be included in the influencing factors of STEM educational intention; thus, readiness was divided into three dimensions: cognition, emotion, and behavior [35; 36; 37] Certain extensions of the DTPB model were established: nine independent variables, four intervening variables, and one dependent variable were used to construct a comprehensive model. Furthermore, corresponding hypotheses were formulated, as shown in Figure 1. Three factors, namely attitudes, subjective norms, and perceived behavioral control, serve as variables that predict teachers' behavioral intentions; perceived usefulness, perceived ease of use, and compatibility serve as variables that predict teachers' attitudes; superior influence, peer influence, student influence, and parental influence serve as variables that predict teachers' subjective norms; self-efficacy and facilitating conditions serve as variables that predict teachers' perceived behavioral control; and cognitive readiness and behavioral readiness serve as variables that predict teachers' self-efficacy.  
The relevant hypotheses are explained as follows: