"هٰذا الْحائِط جَديد."
Translation:This wall is new.
In the audio it is correct as it is. Al-Haa2itu. Maybe if you are confused about the usage of numbers, it can be written in a different way: al-h^á'it^u
Anyway, it sounds OK in the audio
Ah, this is actually how the grammar in Arabic works; By changing the endings of the words to fit into that specific position. Here, the word الحائطُ is the subject of the sentence (the sentence here being "nominal" sentence). Subjects of sentences are said to be in "nominative" status. Words in Nominative status in Arabic, under normal simple conditions like this one, should end with -u (or Dhamma ـُ ).
To what I see, it seems Duolingo is more like teaching the language for a traveler. They are mixing Arabic with dialects, Some words here are not perfectly Arabic. Also, they don't care much about the cases and grammar. I've noted many mistakes in the audios. The audios here are done by a text-to-speech machine which ironically does not know how to speak. On many occasions there were words ending with (-a) where it should be (-u), and many many other mistakes. I don't know where are they going with this but at least people can focus on some vocabulary to enrich their gain a bit and then maybe, if they want to get serious about it, learn Arabic elsewhere with more accurate settings.
Yep. Not sure about Duolingo though but جدار and حائط have the same meaning in general (those who are deep into literature and classical Arabic might differentiate between the two as one being the wall of a garden specifically and one is a general wall for a house or some construction but nowadays in general use, both words work)
What is ئ? The first time it's used and without explanation. Also, how is it different from ءِ or إ or أِ? All four are pronounced the same? Some things in Arabic are >unnecessarily< complicated.
well it is "i" indeed. However notice that أِ is not quite a regular form (looks weird).
Anyway, the drawing of Hamza is actually orthographic. Meaning, the sound is still glottal stop (either I A or U) but drawing it goes under some specific rules (no change in sound). I think such rules were made to help readers read Arabic without much need for diacritics (or harakat).
I won't go into details here, but in the example above, the word حائط has a glottal stop in the middle (Há'iT). So, to draw this Hamza, we have to check the vowel on the last letter before the hamza. Here, we don't have a consonant but we have a long vowel (á) so it is not helping us here. Thus, we go back to hamza and see what is the short vowel of the hamza itself. It is "i" sound, thus we decided to draw it on ى to note that this hamza actually has "i" sound (not A, not U).
Just another example, hopefully that would help:
The male's name Fu'ád (another way to write this is: Fu2ád, using 2 for hamza). Here we look at the consonant before hamza, and it is (F). This (F) has -u vowel. This guides us that the hamza after that should be drawn on U. Hence, the name is written in Arabic as فؤاد