This paper describes the development of a simple handmade conductivity measurement apparatus based on a Kohlrausch bridge with inexpensive materials. We have examined the reliability of this apparatus with standard solutions and then measured juices of vegetables and fruits as well as a sports drink. Comparisons to total alkali content as determined by titration were made. The handmade apparatus was introduced to high school chemistry classes through a lesson on the conductivity of electrolyte solutions. The results showed that the developed apparatus could be used effectively for teaching high school chemistry.