The present study aims to explore whether there are gender-oriented differences in learners' performance when solving equations which require the application of a structure sense. In mathematics one can identify that learners lack a competence of logical observation of algebraic expressions. This deficiency results in the learners' technical approach to exercises, the time they require for obtaining the solution, numerous errors and difficulty in finding the solution. This absent competence is called 'the structure sense'. When studying algebra in high school, this is manifested by the inability to identify a familiar structure in its simplest form, deal with an algebraic expression comprised as a unit as well as identify a familiar structure in its more complex way so that it can be effectively substituted. Gender-oriented studies attest to gaps between the sexes in mathematics. The research population consisted of 48 pupils, 23 boys and 25 girls, learning in the 10th grade. The research instrument comprised six mathematical questions, all of them could be effectively solved by means of a structure sense, except for one question which did not require a structure sense for its solution. Findings of the present research illustrate that the success rates are not particularly high. In most questions, the boys' rate of correct answers exceeds that of the girls. Moreover, there are differences in the choice of solution strategy. The girls opt for the safe and familiar technical way whereas the boys tend to apply an algorithm, namely the effective solution method. It is recommended integrating in the teaching process the strategy of searching special features in the questions in addition to the common algorithms studied in mathematics lessons. As part of a systematic teaching programme, it is advised adding to each study chapter several special questions in order to develop the pupils' appropriate competences.