Table 1. The results of confirmatory factor analyses.

Measurement model	χ2	df	Δχ2	CFI	TLI	SRMR	RMSEA
The hypothesized four-factor model	3889.424	3074		0.944	0.943	0.051	0.035
Three-factor model (combining DEG and DE)	5633.681	3077	1744.257***	0.825	0.820	0.091	0.062
Three-factor model (combining DE and ML)	5860.626	3077	1971.202***	0.809	0.804	0.095	0.065
Two-factor model (combining DEG and SLE; DE and ML)	7818.954	3079	3929.530***	0.675	0.667	0.138	0.084
One-factor model (combining DEG, SLE, DE and ML)	10259.192	3080	6369.768***	0.508	0.495	0.141	0.104

Note: CFI = Comparative Fit Index; TLI = Tucker-Lewis index; SRMR = Standardized Root Mean Square Residual; RMSEA = Root Mean Square of Approximation;

Digital Educational Games = DEG; Student Learning Engagement = SLE; Digital Environment = DE; Motivation for Learning = ML