Do you know what diameter/radius is? The marital life.
I work on a metal cutting machine. At one time, he decided to change the type of activity and was trained from scratch to CNC operator. Later, he taught the basics of other boys. One day, during an explanation to one of the trainees, I noticed that he was not very aware that I was trying to tell him:
Do you understand? Do you know that we measure the diameter and write the radius in the table? Do you know what radiation is?
No, I do not know.
In the sense do you know? What is a diameter?
and no.
And unexpectedly? Do not believe? But the trainee was not even yesterday’s student, but a graduate of Bashkir Construction College in the specialty of industrial and civil construction!!! Later I remembered that during my training at the factory, the mentors asked me this question, and then it seemed stupid to me: "How can an adult not know what a radius is? This is the basis of everything!”
“Well, probably the guy just doesn’t know the definitions ‘by the textbook’,” I thought and painted a circle on paper:
Draw where the radius is, where the diameter.
The trainee paints two more inside my circle.
Impressed by the truth that revealed me all day long, I lie in bed at night. I think: at what point a person learns what the radius / diameter is (this is meant by "not a textbook, but by his own words"; in a domestic sense when a person begins to understand that this is the circle, but here is its radius). And what kind of “thinking” to have to understand this? Technical and mathematical? It is easy to find out:
My wife, wake up. Do you know what radiation is? The diameter? My wife is not a technician, but a philologist-journalist.
Have you fooled anything? What a radius, what a diameter, what an hour of night! What happened?
Long to explain. Can you tell me what radiation is?
The size of the circle. What happened then? What do you do in bed at night?
That is, it is not sacred knowledge that is kept from outsiders. And "not a technician", quietly graduated from school and with geometry, except in the domestic plan, who does not encounter, can at one hour of the night through a dream give the answer, where to dig, in order to find the definition of "radius".
On the evening of the next day I decided to find out, and from what age a person will learn that there is such a term "radius" and asked the daughter-second-grade ("well, in the second grade is still unlikely to pass, - I thought - it will be clear whether it is necessary to study in school or just enough in life to look closely at the sides to find out):
Do you know what radiation is? Or a diameter?
- It's in the circle, here's the point, the central, and there's the distance to the line... - he responds a little confused.
The child in the second grade already knows. But... Something hurts like the definition from a textbook... Did you already go to school?
How do you know? Have you already been to school?
“No,” she smiles, “my mom told me in the morning that you must ask me today and have to learn.