Turkish middle school students’ understanding of the nature of matter was examined and compared to those of US counterparts. Sixteen Turkish middle school students were interviewed using a semi-structured interview guide. The interview explored students’ understanding of the particulate nature of matter in three areas: (1) the composition of the substances; (2) the relationship between particulate structure and macroscopic properties; (3) the relationship between particulate structure and processes. The results indicated that many of the middle school students interviewed could state that matter was composed of atoms. However, the majority of them were not able to use this understanding to explain macroproperties or processes of matter. Compared to the US students, the Turkish students could use terms more appropriately in describing the microparticulate nature of matter. However, when students tried to explain the macroproperties or processes of matter, the US students offered more complex and detailed explanations
