Today’s lesson focused on understanding the pH scale, which ranges from 0 to 14, and identifying common laboratory and household chemicals as either strong or weak acids and alkalis. A pH of 7 indicates a neutral substance, like water, while numbers below 7 indicate varying strengths of acids, with the strongest at pH 0. Numbers above 7 indicate alkalis, with weak alkalis starting at pH 8 and the strongest at pH 14, as indicated by the color gradient from green at neutral to deep red for strong acids and deep purple for strong alkalis.