"no notebook" is a very unusual English usage, reserved for emphatic statements of some sort, often about exceptional things, while "not a notebook" states that the thing is simply not a notebook, but something else. For example: "This is not a notebook, it is a formal book on Russian grammar". But "This is no notebook - it is a complete plan for the end of the world".
Here's the way I learned for German and Russian when gender agreement with the noun is actually required, and when it isn't. Unlike Italian and Spanish, where agreement is always required, in Russian and German, there are times when you should use the neuter form instead.
If это is separated from what it equals (это = тетрадь) by a verb, or by the implication of a verb (since you do not actually see "to be" in this sentence), then you should use the neuter form (это). Agreement is not necessary. However, if это is on the same side of the sentence as what it equals, and is NOT separated by a verb (visible or implied), then you must make it agree with that noun, and you would say эта тетрадь.
I will illustrate this for you in German as well, since the language structure and vocabulary are much closer to English and it may be easier for people to see there. :-)
Consider the sentence, "Das ist nicht eine rote Blume." (That is not a red flower.) "Das" (That) serves the same purpose as это did in our Russian example. It is neuter. However, Blume is a feminine noun. But notice what happens with "rote," (red, f.) which is NOT separated from Blume by the verb ("ist"). The masculine/neuter form of this word is "rot." But because it is on the same side of the sentence as "Blume," it must agree in gender, hence "rote Blume."
As you have likely noticed, this would not be proper Italian or Spanish, since agreement is expected in Romance languages across the entirety of the sentence. But in Germanic and apparently at least one Slavic language, that is not true.
Please let me know if this explanation helps any!
Compare. Тетради has a very clear и sound at the end.
One of the tricks to hearing something is to pronounce it several times over, starting at the syllable level very, very slowly, and then building up a word, so that it forms in your mind. When you brain knows what to expect, it will hear things a lot more clearly. That means learning the rules of pronunciation, then adjusting words as you hear them spoken by native-speakers (or computers, which often do a good job of it).
I speak every sentence and phrase in every exercise in Duo, even if it's not a dictation exercise, to practice sounding the words, playing back the audio, comparing, trying to get it close. Takes a lot longer to do each exercise, but ultimately helps learn aural skills much more quickly.
No, you couldn't. You've indicated why: There's no "my" in the sentence.
Also, мои is the plural form of "my", and тетрадь is singular feminine, so you'd have to use моя тетрадь.
The plural form is mои тетрады = "my notebooks"
There's a huge difference between ь and ы. ь is not pronounced, but affects the pronunciation of the consonant before it. ы is a vowel with a definite pronunciation, as in мы vs. тетрады. If you want to hear the difference, copy the words into an online translator like Google Translate, then press the little speaker icon, and it will say the words for you. Also, for native speaker pronunciation, try forvo.com, but there's a more limited number of words pronounced there.
The letter does not make any sound in the modern language. It modifies the pronunciation, though:
- we use it to mark patalisation when there is no vowel to show it: пять, тетрадь, мальчик
- or to keep the Y-sound of a iotated vowel: семья, вьюга, льёт
- it is also used in some loanwords like медальон to actually spell a Y (an original Russian word usually be spelt медальён instead).
There are a few cases where it does not matter:
- ш, щ, ж, ч are sometimes spelt with a ь right after. They are pronounced the same regardless
- in reflexive verbs, -ться (infinitive) and -тся (3rd person singular) are both pronounced цца