Proportional reasoning has been emphasized. NCTM (2000) suggested that proportionality is an “integrative thread that connects many of the mathematics topics.” (p. 217). Inhelder and Piaget (1958) identified proportionality within Piaget’s stage of formal operational reasoning and illustrated it as ability to aware a secondary relationship between two pairs of quantities. Lamon (2007) proposed that proportional reasoning occurs when students recognize co-variation of quantities and in-variation of ratio simultaneously. It was reported that students use different strategies according to the types of given proportion problems. For example, Cramer, Post and Currier (1993) found that students made use of several strategies such as unit-rate, factor-of-change, fraction, and cross-product algorithm in solving proportional problems categorized as a missing value, numerical comparison, and two types of qualitative situations. This implies that the use of diverse proportional situations is helpful to analyse students’ proportional reasoning ability.