Translation:They read the newspaper in the morning.
Forenoon? This has to be some bad translation, I've never even seen/heard the word!
I can't say I've ever used it, but it is a word (though the Oxford dictionary says that it is chiefly North American and Nautical) but it refers to the morning from sunrise until noon, whereas "formiddag" is more late morning as luckygusty says
"forenoon" (one word) is not used in everyday English, whether written or oral. Most English speakers have never used the term, though it survives in some legal documents, court rules and legislation.
Example: the daylight savings time provision, subsection 2(3) of the Time Definition Act, Nova Scotia, Canada:
2 (3) Notwithstanding subsection (2), in each year between two oclock in the forenoon of the first Sunday in April and two oclock in the forenoon of the last Sunday in October time shall be reckoned as three hours behind Greenwich mean solar time.
Example: Rule 9(2) of the Queen's Bench Rules of Saskatchewan, Canada:
9 (2) All documents received by the local registrar by mail or by prepaid courier prior to 10 o’clock in the forenoon shall be deemed to be received at 10 o’clock in the forenoon and prior to any documents received at the office of such local registrar in person at 10 o’clock in the forenoon.
I wrote: "They read the newspaper about the morning"
How would you say this sentence if they are reading some kind of educational material about the different aspects of mornings?
I would assume how you've put it would be one way of expressing that, but I do know that om has another meaning when referring to time.
e.g. One can say: "Vi snakker om bogen" - We talk about the book. As well as: "Vi ses om en time." - I'll see you in an hour. And also: "Vi ses om klokken fire." - I'll see you at four o'clock.
In the last practice, the translation for "formiddagen" was "the mornings". Now it is translated by "forenoon". That's confusing!