In this online interactive simulation, learners will test the pH of liquids like coffee, spit, and soap to determine whether each is acidic, basic, or neutral. Learners will visualize the relative number of hydroxide ions and hydronium ions in a solution, and they can switch between logarithmic and linear scales. Learners will also investigate whether changing the volume or diluting with water affects the pH. They can experiment by designing their own liquids! This activity includes an online simulation, sample learning goals, a teacher's guide, and translations in over 30 languages.