*5.2.2.1 Validity*

All the questions of the FTI-ENES instrument are valid with high validity indices. The average validity index for A-tier, R-tier and B-tier are 0.46, 0.45 and 0.53, respectively. These values confirm that the FTI-ENES is powerful for identifying students' unscientific understanding in the area of electrolyte and non-electrolyte solutions. The detail values for each question and each tier are provided in **Table 2**.


#### **Figure 10.**

*Example of a four-tier instrument in the FTI-ENES.*


*Insights Into Global Engineering Education After the Birth of Industry 5.0*


**Table 2.** *Validity indices of the FTI-ENES.*
