I sort of guessed the answer here.
Am I correct in thinking that "миска" is the gen. singular, "миски" is the nom. plural, and I've no idea what "миску" is?
«Ми́ску» is Accusative singular.
Ми́ска ‧ cognate with mesa, as in table [ mēsа «стол», латин mēnsа ]
Ми́ска ‧ Nomi ‧ Geniti ‧ Dative ‧ Accus ‧ Instrum ‧ Prepo
Singu ‧ миска ‧ миски ‧ миске ‧‧ миску ‧ миской ‧‧ миске
Plural ‧ миски ‧ мисок ‧ мискам миски ‧ мисками ‧ мисках
‧ Ми́ска ‧ noun declension ‧ cooljugator.com/run/миска ‧
‧ Ми́ска ‧ fem ‧ bowl, tureen ‧ en.wiktionary.org/wiki/миска ‧
‧ Ми́с-ка ‧ ‧ ru.wiktionary.org/wiki/миска ‧
‧ Ми́ска ‧ a bowl shaped dish, container, even a mountain [ Гора Ми́ска ] ‧ ‧ от миса ‧ ‧ ru.wiktionary.org/wiki/миса ‧
I actually think миска is nominative singular. миски is probably genitive singular.
What exactly does this refer to? When I think миска, I think of a large round container used when baking: http://goo.gl/DYLNQ8. I believe a bowl that you eat cereal or soup (http://goo.gl/GxNuXR, https://goo.gl/lwvgN2) from is called глубая тарелка ‘deep plate’, or at least that is what my mother calls it. Please, can anyone verify? I don’t know where to look for a good definition of миска.
You can use a dictionary if you wish—the only problem is that definitions of many everyday items want someone to finally update them. «Ми́ска», «пиа́ла» (from Persian peiaale) and sometimes «пло́шка» all refer to a bowl, though it is миска that you'll see in the shop.
In some places, especially in Siberia and the Russian Far East, чашка is used as the name for a bowl. Well, it is a good place to remember that we teach Moscow/St.Petersburg Russian when it matters :).
You should have used ка́ши 'of kasha', not ка́шей 'with kasha'.
The sentence «Я ем ми́ску ка́шей» 'I'm eating a bowl with/using kasha' is completely grammatical, but probably not very useful. Theoretically, you could have freezed your kasha so that it's iced, and made yourself a spoon out of iced-kasha; and миска can be made of something edible, e.g. out of chocolate, so technically this sentence is not completely impossible... :D
Thanks szeraja! Google translate doesn't always give the right form. I just finished the Ukrainian course. Good to see you on the Russian one too!