“Physical world was established by symbols and units” (Uhden & Pospiech, 2009, p.30), and as far as symbols and units are concerned, science –specifically mathematics and physics- come to the fore. Literature suggests that mathematical background is vital for making physics, and so, to be able to solve physics problems, mathematics is a prerequisite for the majority of physics courses (Nguyen, 2011). Mathematics and physics fields share several common concepts in order to make sense of the world. One of these concepts is accepted as a prerequisite for being able to make science. 

Mikula and Heckler (2013) explain “essential skills” as prerequisite skills for university level course works, and put metric prefixes and conversions under this definition. In their study, being prerequisite skills for their course, engineering students either did not receive instruction or got only little instruction on these concepts. Their study findings revealed that engineering students had difficulties with such essential skills, although they were already supposed to have knowledge on them. More specifically, they were expected to be able to convert metric units such as converting micrograms to kilograms and/or centimeters to nanometers etc. They further add that having essential skills is a must for problem solving, and students should have almost full accuracy with these skills. When their accuracy decreases below 80%, it gets harder to ensure student success. In their study, engineering students’ low performance was claimed to be worrisome especially when it is taken into account that they use metric conversions constantly while solving problems in engineering.  

In the literature, there are several other studies indicating that students have difficulty with unit conversion. For example, in a recent study, Cebesoy and Yeniterzi (2016) found that 7th grade students mathematically struggled with unit conversion while they were solving physics problems related to force and motion unit. In another study by Bagno, Berger, and Eylon (2008), it was also stated that manipulating units was among students’ difficulties in problem solving. In Aydın (2011)’s study, it was found that first-year science teaching students had mathematical misconceptions and made mathematical mistakes in General Chemistry II course as they had deficient knowledge of mathematics including unit conversion. Birinci Konur and Pirasa (2010) also stated that the participants in their study mostly made mathematical mistakes rather than in chemistry as they had lack of knowledge of mathematical concepts including unit conversion. More specifically, the students in their study had difficulty with converting milligram into gram. The researchers concluded that science teaching students had deficient knowledge of unit conversion, and such deficiency risks their science literacy skills.

While the understanding of the concept of unit conversion is a prerequisite for making science and students’ have serious difficulties with converting metric units, it is vital to examine and try to understand their difficulties in order to be able to make suggestions for educators. Thus, in the present study, the aim was to investigate prospective science teachers’ knowledge of and difficulties with unit conversion. The research questions to answer were:

1)      To what extend the prospective teachers can convert metric units?

2)      What are their major difficulties with unit conversion?

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