Teaching chemistry necessitates hands-on activities to help students deeply understand chemistry concepts and relate scientific principles to daily life. However, constraints in accessing laboratory equipment and materials pose significant challenges for educators in conducting experiments. This paper proposes the development of a pH indicator gel derived from natural plants and juices to enhance the teaching of acid-base topics. The aim is to foster interest and inquiry in students through the predict-observe-explain (POE) strategy. The pH indicator gel was formulated by combining agar gel with various natural indicators and immersing it in different buffer solutions with pH values ranging from 2 to 12. The resultant color changes in the pH indicator gels were compared to the colors of reference solutions spanning the same pH range. Experimental results demonstrated that the gel modified its color in a manner akin to the color change exhibited by the corresponding extract indicator in the buffer solutions across the entire pH range. Moreover, the agar gel was able to be reused multiple times while continuing to display alternating color changes in response to the pH of the solution. The pH indicator gel was utilized in teaching acid-base topics to a group of 24 student teachers in Cambodia. This hands-on activity stimulated interest and curiosity in the student teachers, leading to more engaged observations during the experiment. Feedback from these student teachers highlighted that the pH indicator gel was an effective teaching aid for conveying acid-base concepts and helped boost their engagement in laboratory experiments.