"The class is" is not wrong, it just depends on how you view "the class". In fact, I would lean toward "is" rather than "are" because I consider the class as a singular group rather than individual students. Anyway, have a look at this link on singular plurals:

Singular or plural for groups of people

Though there is nothing wrong with saying "silver hair," more people would tend to say "gray hair" to describe his hair color.

Personally I still prefer ARE" in the original context. Also I have silver hair being in my mid-seventies. LOL. we call ourselves Silver surfers when on line.

The old song "Silver threads among the gold is" so much more beautiful than Grey Hair among the gold.

this is a very old recording of John McCormack singing the above very popular song:

‪John McCormack Silver Threads Among The Gold‬‏ - YouTube

Darling, I am growing old, Silver threads among the gold, Shine upon my brow today, Life is fading fast away. But, my darling, you will be, will be Always young and fair to me, Yes, my darling, you will be Always young and fair to me. Chorus: Darling, I am growing old, Silver threads among the gold, Shine upon my brow today; Life is fading fast away.

Thank you, dogsbody70, for your kind lesson.

....he's just talking something funny.....(Wrong)
....he's just saying something funny..... (Correct)

All the class are smiling and staring at him.(wrong)
All the class are smiling and looking intently at him. (correct)

If we stare at someone-- it can seem rather rude. We may look, watch or gaze but staring is not appropriate in this context. Please don't stare at me, it makes me feel awkward and embarrassed.

Thank you, RobinMask, for taking your important time for me.
left edge (wrong)
left side (correct)

'The teacher may be over 40, judging from his silver hair' sounds less natural.
'Judging from his silver hair the teacher may be over forty' sounds more natural

The class seems to be an international class, and there are Caucasians, a Hispanic and an African American as well as her. (wrong)
The class seems to be an international class, and there are Caucasians, a Hispanic and an African American as well. (correct)

I understand this point, as well. :)

Thank you, kuuzoku, for the link.
It is interesting.
Singular/plural -wise, to make the long story short, both are OK, though the point of view are different. Right?

And
When it comes to silver/gray hair, I think of Japanese Keigo system.
Sonkeigo and Kenjogo.
I think "silver hair" is sonkeigo, while "gray hair" is kenjogo, or just neutral expression.
From the Japanese-keigo-system point of view, if someone says "My silver hair's got too long, so I'll go to the barber tomorrow", he seems arrogance.
"My gray hair's......" is humble enough.

If I saw a respectful 'gray hair' woman, I would say, "your silver hair is so beautiful!" instead of "your gray hair is so beautiful!"

What do you natives think?
I don't think it is not just the way of Japanese thinking, but worldwide.

In other words, when the polite expression would be proper, one should choose "silver hair".
When neutral or we don't have to consider any respect, we would choose "gray hair", I think.

edit)
On second thoughts;
When the black hair and the white hair intermingle, we should call it "gray."
When there is no black hair, and only white hair, we would call it "silver". Right?

Grey is a type of colour, so if the whole head of hair is only white then we would call it grey. If the head of hair was black and white intermingled, then we would probably say 'he/she has grey streaks', this is because the whole hair isn't grey, but it is streaked with grey. So in your first example it's 'grey streaked' and the second it's just 'grey hair'.

As for the difference between 'silver' and 'grey', you are right that 'silver' sounds far more polite and complimentary than 'grey' does. Personally 'silver' sounds more poetic to me, something you would probably hear in a novel or a poem, because in everyday life 'grey' is more widely said, but - if you wanted to compliment somebody - 'silver' would also be acceptable, because it does sound far more poetic, thus more of a compliment.

So kind of like "She has the most beautiful silver hair" for a compliment, and "She has grey hair" to just state a fact :)

I think SILVER Hair is more poetic. I love to see men with a head of silver hair. especially when brushed back-- So many men lose their hair and go bald-- so its wonderful when older men really do still keep their own hair-- I feel they look really distinguished. Our musical director
Had a wonderful head of silver hair and many of the women in his orchestra almost swooned over him-- including myself. But his wife kept a strict eye on him so no flirting allowed.

Many years ago I had a crush on a glamorous American-- clothes designer-- He bought several of our dogs- He had a full head of White/blonde Hair.


Superman, I think if you were to compliment a lady on her hair you would probably say that she looks charming. I don't think you would mention the colour of her hair.

Thank you friends.
According to your advices, I think I could grasp the nuance of the two colours when modifying someone's hair.

'Grey' is the orthodox, standard and ordinary expression for natives.
'Silver' is more poetic, in other words, some kind of figurative expression, which is used with a special intention.

BTW, I've got confused which spelling is alright; grey or gray.
So I looked for a dictionary and found that both are correct.
Again, one of the BE and AE differences. :eek:

Most Commonly Misspelled Words and Their Common Misspellings Grey or Gray.

Thanks, for the information.
It's interesting. I've already known some of them, including the both spelling.

Yet, I don't know about seven words on the list. I'll check it out. ;)