Explain what is acidic and alkaline for year 7 student

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Welcome to chemistry! Today we'll learn about acids and alkalis using something called the pH scale. Think of it like a special ruler that measures how strong substances are in a particular way. The pH scale goes from 0 to 14, with acidic substances at the low end, neutral substances in the middle around 7, and alkaline substances at the high end. Now let's learn about acids! Acids are substances that often taste sour, like lemons or vinegar. But remember, you should never taste chemicals in a laboratory - it's dangerous! Acids have pH values below 7 on our scale. Some common examples include lemon juice with a pH around 2, vinegar with a pH around 3, and stomach acid which is very strong with a pH around 1. Acids can be strong and dangerous, or weak and safe to eat.