Scientific instruments and apparatus are noteworthy exhibits in museums. Other than showing evolution of technology in achieving lower limits of detection, these pieces are useful educational resources. Development of specific instrument rarely drastically changes the principles of operation. Showing parts and techniques on old or broken pieces can help students to engage and understand newer scientific instruments. During exhibition on Science Festival 2018, a set of key pieces were shown. Visitors found that the most interesting one were apparatus for continual bidistillation of water (1961, Glass Factory Pula, Croatia) and pH meter (1940ties, O.M.A.P., Ottica Mecc. App. Di Precisione, Italy). [1] The distillation apparatus was attractive to visitors and then used to explain the hydrological cycle in nature. pH meter wasn’t as visually attractive as distillation apparatus. The most curious visitors had chance to learn about pH values in body and different house chemicals. This seemed to be very important, because some visitors were convicted that human bodies are basic, according to pH scale. These exhibits are relevant educational resources for education of elementary, high school and faculty students. Science Festival exhibition showed that educating adults is also important. Adult visitors seemed not to be enough critically oriented towards magazine articles that claimed that human body pH was overall above 7.We owe many thanks to Ana Đorđević and Zorana Đorđević who photographed selected pieces. We also thank Katarina Kojić, Sara Knežević, Milica Čalija, Katarina Tomić, Olivera Stevanović, and Nenad Zarić for their cooperation during the exhibition at the Science Festival 2018