Science learning is based on understanding of different scientific phenomena and classification of scientific concepts. When individual's ideas are different from scientifically accepted facts, they are called misconceptions. They are not based on gender, age, or cultural constraints. Misconceptions are formed due to individual's diverse personal experiences. Several studies have shown, that students hold the most misconceptions regarding the concepts of vertebrate, invertebrate, reptile, amphibian. Students mostly classify based on criteria, that are available to them at a given moment. They mainly focus on the animal's habitat, movement and the number of legs. We conducted a quantitative survey, where we were interested in how and on the basis of which characteristics of animals students classify them in the system. With combination of questionnaire and test technique, we wanted to investigate how the student’s animal classification and the occurrence of misconceptions change with age, and what are the criterias students use in classify the animals. We also wanted to see, how an interest in learning about different animals changes regarding gender and age, and an impact of nature visits on the occurrence of misconceptions. Our study involved 239 students, from sixth to ninth grade of primary school. The results of the study showed, that the animal classification performance does not improve with an age. Hoewever, the study has shown, that seventh and eighth grade students are better with classification than sixth and ninth grade students. We also discovered, that interest in animals decreases with age, and that boys show a higher interest in learning about certain animals than girls - mainly those animals, that often provoke negative emotions in humans (fear, disgust, anxiety, etc.) We have found, that students classify animals primarily based on their habitat, anatomical features, and their movement patterns. Visiting the nature does not play a significant role in classifying performance of the students.