The Russian word for ‘what’ is что. Although it is written with the letter ч, the nominative/accusative form of the word is most commonly pronounced [што]; in the other cases we do pronounce ч as ч. It occurs in all six cases:

Notice that the only difference between the prepositional and instrumental forms is the двоеточие “double dots” over the prepositional form.¹ Remember that the Russians usually do not usually write the double dots, so context will have to tell you how to pronounce those forms. Some sample sentences:

Somewhere in school every American is taught the rule “never end a sentence with a preposition.” For English it's an assinine rule that has no reasonable justification in the living language.² However, for Russian the rule is real and alive. It's not an artificial rule, as in English, but rather a subconscious part of the living language: no Russian will ever end a sentence with a preposition, not even accidentally. So whenever you are translating a question from English to Russian, and the question ends with a preposition, you need to move that preposition to before its object and then translate. Thus:

Other examples:

Notice in the last example we can leave the preposition out of the response in English, but in Russian you must retain the preposition to justify the case of памятник.

¹ The double dots symbol is often called a diaeresis or an umlaut. The former is theoretically used to indicate that a vowel is pronounced as a complete vowel (not a diphthong) when preceded by another vowel with which it might blend. The latter is theoretically used to indicate that vowel is fronted. Since neither of those instances prevails in the е/ё distinction, “double dots” is a sensible name for the symbol.

² Of course, one can't mention this rule of English without mentioning Winston Churchill's famous definition: “A preposition is a word you can't end a sentence with.” I actually doubt that Churchill said it, but it's too fun not to mention.

The word я ‘I’ is a personal pronoun that declines like this:

In American English there are a couple of problems with the word ‘I.’ First off, in conversational English we often say ‘me’ where we should say ‘I’ in the literary language. Thus kids often say things like “Me and John went to the store” or “It's me” when theoretically we should say “John and I” or “It is I.” The Russians never make that mistake. They always use subject/nominative form in the right place:

Other examples:

¹ Although this sentence is theoretically okay, the Russians usually say it differently. We'll address the better usage in an upcoming entry on the word мы.
² Although theoretically one should say “It is I” in this context, no normal American will do so. Only pedants say “It is I.”

The word он is a personal pronoun that declines like this:

The «н» versions of the pronoun occur when the pronoun is the object of a preposition.

Он refers to masculine singular nouns, which can be either people or things, so sometimes it is translated as he/him, and sometimes it is translated as it. In other words, if you are refering to a врач doctor, then the sentence must be translated with he/him, and if you are refering to a грузовик truck, the same sentence must be translated with it:

In casual conversation it's common in America to say things like “Me and John went to the store,” especially when we are children. Schoolteachers then try to beat us out of that habit and make us say “He and I went to the store.” Because of that influence, English speakers may be tempted to say things like «Он и я ездили в магазин» in Russian. While theoretically one can say that in Russian, no one ever does. Instead it gets rephrased as “we with him” «мы с ним». Of course, it would be ridiculous to translate that as “we with him” in English; you still want “he and I” or just plain old ‘we.’

There are several ways in Russian to express the idea of “the same” in the sense of “the same house” or “the same country.” One way is to use один (which is also used as a cardinal number), and another way is to use «тот же». For instance, if you are just starting a conversation, you could say:

Oddly enough, in that context you cannot say «в том же доме». What's the difference? Essentially it's this: in order to use «тот же» the noun must have previously been mentioned in the conversation. For instance:

Another example. If you are for the first time mentioning your transportation over the weekend, you might say:

But if you have already mentioned the train car, then you use the other phrase:

Of course, the phrases can be used in other cases as well:

Sometimes один and тот же combine into a single phrase «один и тот же», but we'll save that phrase for another time.

The Russian phrase for “each other” is formed by saying the word друг twice in a row. The second друг occurs in a case other than the nominative, i.e. you can find these five forms:

The case of the second друг depends most often on the verb in question. If the verb requires a direct object, the second друг shows up in the accusative case; if the verb requires a dative object, the second друг shows up in the dative case. Likewise genitive — genitive, and instrumental — instrumental. Here are some examples:

If the verb requires a prepositional phrase as its complement, then the preposition comes between the two другs:

Native English speakers, of course, will be tempted to write things like «Мои сёстры постоянно сплетничают о друг друге». And truth to tell, native Russians will say or write something like that, but it is not considered good written style.

Interestingly enough, sometimes the Russians substitute дружка for the second друг. Thus you get:

That makes the phrase much more informal and conversational. For instance:

I was interested to find the phrase as well in a site devoted to Russian folk magic. Here is a spell people use to help repair a family fracas:

You'll notice that жгут, обходят and читают are not command forms but third person plural verbs. In the translation they are rendered as imperatives to make the English flow better.