In this research, a new test for understanding simple fractions has been developed for students at the beginning of lower secondary education. In many countries, mathematics education in Grade 5 builds on elementary students' developing concepts of fractions. Understanding fractions causes many difficulties for students, and research on mental representations of fractions suggests that different visualizations may be helpful in teaching and learning. The sample consisted of 124 5th-grade students, and the reliability of the test proved to be high (alpha=0.95). Out of the three types of visualization, the pie chart was the easiest to recognize, and ½ (half) proved to be the easiest, and ? (one-third) the most difficult to be recognized. The type of visualization has a stronger effect on students' performance than the type of fraction (unit versus non-unit fractions). Most surprisingly, students were better at recognizing 2/4 and 2/3 than their unit fraction counterparts, ½ and ?. The test was supplemented by questions on attitude towards learning fractions.