This is purely a question out of curiosity. For those responsible for teaching metric prefixes, have you found any actual applications where deci, deca, or hecto are the preferred prefixes for discussing measurements?
As someone who lives in a place where metric is used, we never use those prefixes other than in math class.
In Hungary we have used deci- and deka- quite often. In daily measurements, not just when cooking but also when shopping, deciliter, and dekagram are used all the time. Even at a bar, to order a shot they would use deci "Give me a half deci" means "give me a half deciliter" for cognac or other spirits. Hecto not so much. I don't remember ever using that.
If you're in a farming community or in an ag. class, hectares are a unit of land measure. Hectare is to acre as centimeter is to inch. A standard family farm is about 80 hectares.
We did use hectar (hektar) as a land measure but not hecto- as a prefix. And of course centimeter, decimeter (although not as much). Centiliter is also there but not used as much as deciliter is more common. I think in chemistry, etc where you measure much smaller volume. The most common altogether were millimeter, centimeter, meter, kilometer, gram, dekagram, kilogram, deciliter, liter. We also had an old measurement, "mázsa" which is 100 kg, and tonna, which is 1000 kg.
Beer and cider bottles that aren't marked in ounces may be marked in milliliters, centiliters, or deciliters, depending on the size of the bottle. What makes the metric system so easy and cool, though, is that the prefixes are absolutely the same no matter what the base unit is (or if the unit even exists: there's a dreadful joke that, since Helen of Troy's beauty could launch a thousand ships, the amount of her beauty required to launch just one ship is a millihelen). So once one grasps the system, it's easy to figure out how much of the unit the prefixed-unit term is referencing. Oh, and there's this: the common bigger-than-one prefixes are from Greek (deka, 10; hecto, 100; kilo, 1000), whereas the smaller-than-one prefixes are from Latin (deci, 1/10; centi, 1/100, milli, 1/1000). Deka gives us the word "decade", or ten years; Latin decim is the source via French of the word "dime", 1/10 dollar, a.k.a. ten cents.
