The Italian phrase cited by this dictionary is properly i paperi voglion menare a bere l’oche and means the goslings want to take the geese to drink. I can sort of picture the conversation: "Granny, don't forget you need to poke a hole at both ends of the egg. What they don't do is actively suck out the yolks and the whites, like some kind of breakfast food vampire. To teach fishes to swimme; (an idle, vaine, or needlesse labour) we say, to teach his grandame to grope ducks.

Teaching grandmother to suck eggs is an English language saying that refers to a person giving advice to another person in a subject with which the other person is already familiar. Sucking an egg from a shell that has a single hole in it is likely to be no more efficient than "shooting" a beer from a can that has only one opening in it. Teach your Grannum (Grandame) to suck Eggs (A Reproof to those, who think they have more Knowledge than the whole World, and will be ever and anon teaching those who have had more Experience than themselves. Nevertheless, the technique for doing it properly is easy to learn and requires no great skill, so it isn't something that a person of advanced years living in England in the late 1600s would not have known.

But, I would also hope that experience brings with it the maturity and capacity to allow for some enthusiasm from others. A person who followed Wikipedia's method and poked a single pinhole into an egg would probably find the subsequent sucking operation far less satisfactory than anticipated.

Stevens, of Francisco de Quevedo (Spanish author): [2] "You would have me teach my Grandame to suck Eggs". We’re non-experts (to put it mildly) marketing to experts, and that can make us very nervous indeed.

And above all, emphasise that we’re largely improving what we do already rather than necessarily doing new things. Dating back to the early 13 th century, it is the oldest of the English terms of relationship formed with grand-. If teachers are skeptical or cynical about being presented with ideas in CPD, it might well be because they’ve been burned too many times with egg-sucking presentations.