Saber and poder may both translate to "can" in English. "Saber" is used if you refer to a particular skill that can be acquired (I can write, he can't read, she can swim). "Poder" ist used when referring to permission (can I open the window?) or when "being able to do sth" does not depend on skill acquisition but on other factors (i cannot come because i don't have time / money or because I am sick...)
I know how to swim well, but I can't (no practice/muscles anymore). :p
So, basically, we should just be cautious and use "how to" for saber even though "can" works in some of them. -sigh-
And, seriously, whatever "can"/"know how to" distinction you try to make for writing, can be made for other verbs. It can be done for 'read', where duolingo let us use "can" -_-
It's not there.
As in English, there are some subtle differences in meaning in the different variations here.
If you want to say that they can write: Ustedes saben escribir (on the meaning of, they are literates)
If you want to say that they know how to write: Ustedes saben cómo escribir (meaning they just wrote some fantastic stuff and it's amazing)
The problem is that in every day language "cómo" is generally omitted and really the full sentence would be something like Ustedes sí que saben cómo escribir. In everyday language, when everybody is in context and knows the verb (the action) the sentence could be shortened up to "ustedes si que saben"
It is becoming more and more common in Spanish to use the English expression "know how", mostly because there are a lot of people who reckons they sound way cooler if they use English words, but also partly because they do not put the effort on the language.
In Spanish you have also the verb Conocer and conocimiento , and saber y "saber cómo". The former matches to the English to know, stripped. Meaning "in a conceptual level" i.e. I know this guy, I know Riemman theories, I know my people, ... Whilst Saber should be used more in the practical sense: I know how to clean the carburettor, I know how to get there and I know how management works.
Sure it is a thin line, but now we smear it because there is something more: Saberse, reflexive which goes mostly for things you know by heart. So, in Spanish the question "Do you know how to get there?" has two possibilities: ¿Te sabes el camino para llegar allí? ¿Sabes cómo llegar allí?
My understanding is that the difference is on experience, so, if you know that the other chap has done the way as a passenger or something, you can use the first implying he has gone through it and you question whether he remembers it or not. The second can be liberally translated as "did you look up the way?" In a more general context, just if he knows any way to get there.
All that said, I would be the first to admit that the subtle differences may be omitted by native speakers and you will hear "Tenemos el know how", unfortunately
Thanks for the fantastic explanation. That is the most detail I´ve ever seen on the sometimes fine line between between saber and saber cómo and sí que saber, as well as saber vs conocer. There are plenty examples published in the world when it is obvious that only saber or only conocer would fit, but not enough on the subtlties. I´m going to copy this awesome explanation onto my evernote database, and maybe share it elsewhere with some friends if you don´t mind Muchísimas gracias por su explicación y paciencia.
The pronunciation of "escribir" definitely ends with a sound that is represented in English by "sh". I tried it on Pons online dictionary which gives a choice of European Spanish or Mexican Spanish, presumably simular in other Latin American countries. The European Spanish does not have this sound, but the Mexican Spanish does. I know that Duolingo is largely there for Americans who want to talk to their neighbours, but is it possible to have the option of a Spanish voice for us Europeans? Also, I understood that Spanish, unlike English or French, always has a one-to-one relationship between its sounds and letters. Is does not seem to be the case here.
A great discussion on why the word "how" was omitted from this sentence, but the words: "when," or "why," could have fit the model equally well. To be found wrong for the lack of using "how" (when the context of the sentence is unknown) seems to be expecting a lot from beginning students. DL should consider reasonable alternatives under the circumstances or indicate in some form that "how" is the preferred choice.
Why "She can read" is correct for "Ella sabe leer", but "You can write." is not correct for "Ustedes saben escribir." ? It's a double standard.
Sorry, brendan, you are wrong. "Ustedes" is the formal plural "you" (also informal everywhere except in Spain) and nothing else! It NEVER means "they."
"Ellos" and "ellas" are neither formal nor informal. Same with the subject pronouns "yo, él, ella," and "nosotros/as." Only the four "you"s in Spanish are designated as formal (usted, ustedes) or informal (tú, vosotros/as or ustedes).
This is fundamental grammatical lesson: the English "can" + infinitive covers two distinct Spanish concepts of poder + infinitive (physically able to do something) and saber + infinitive (knowing how or possessing the skill to do something). The English "we can swim" translates as both "sabemos nadar" and "podemos nadar", but conversely "we know how to swim" in English implies that we might technically know how to swim, but lack the physical ability or practical knowledge to prevent ourselves from drowning...