In Chemistry, I learned about acids and bases and hoe they react with pH indicators. For example acids, such as vinegar and lemon juice turn blue litmus paper red. Bases such as oven cleaner turn red litmus paper blue. Because the paper reacts to the pH of the solution. You can also tell if a pH indicator is acidic or basic using the pH scale anywhere below level 7 is acidic and anywhere above 7 is basic. Level 7 itself is neutral/ pure water. we had to determine if a solution was acidic or basic based on its color change. I used my critical thinking skills to see how much and what color the substance to determine if the substance is acidic or basic.