Primary standard

Well, a primary standard is like a super duper special ingredient that we use to measure other things.

Imagine you're making a cake and you need to measure out flour. You could use a measuring cup, but how do you know if the measuring cup is accurate? Well, that's where the primary standard comes in.

A primary standard is a substance that is so pure and stable that we can use it as a reference point to measure other things. For example, we might use a primary standard called sodium chloride to measure the amount of chlorine in a swimming pool.

To make sure the sodium chloride is really a primary standard, scientists have to do lots of tests to make sure it is super pure and doesn't change over time. That way, when we use it to measure other things, we can be confident that our measurements are accurate.

So, the next time you measure something and want to be sure it's accurate, just think of a primary standard like a superhero that swoops in to save the day and give you the most accurate measurement possible!