Throughout the world scientific reasoning (SR) is a valuable and desirable ability to gain deeper understanding of science in all grade level. In the current study, we first adapted the SPR-I (7) which consists of seven items with three sub-dimensions as the experimentation, the understanding the nature of science (NOS) and the data interpretation, based on the guidelines of the International Testing Commission. Then, we explored several individual differences in SR scores. We gathered data from 533 elementary students in 4th, 5th, and 6th graders. The Rasch analysis results showed that the model-data fit was acceptable and was exactly the same reliability (EAP/PV = 0.48) as the original SPR-I (7). In addition, the test-retest reliability results (Cronbach's [alpha] = 0.77) showed an acceptable reliability. Furthermore, the results regarding individual differences, it was found that there was no statistically significant difference in terms of gender and region. However, there was a significant difference in the total SR scores and sub-dimension of NOS between 4th and 6th, and 5th and 6th graders in favor of 6th. According to parental education levels, a statistically significant difference was found in favor of those with higher level in the total SPR-I (7) and the sub-dimension of experimentation. In conclusion, the current study shows that the Turkish version of the SPR-I (7) is a valid and reliable measurement instrument that can be used to measure SR in 4th, 5th, and 6th graders and contributes to the literature in terms of addressing the individual differences affecting SR at the elementary education level.