Questions & Answers about من میدانم که این جادو است چون آن را دیدم.
Why do we use ke here, and can I skip it like I sometimes skip "that" in English?
The word ke connects a verb of knowing, thinking, or saying to the clause that follows it, just like "that" in English. In spoken Farsi, it is very common to drop ke, so saying man midānam in jādu ast without it is perfectly fine and sounds very natural.
Why does the sentence use midānam for "I know" instead of mishenāsam?
Farsi has two different verbs for "to know". You use dānestan (which gives us midānam) when you know a fact or a piece of information. You use shenākhtan (which gives us mishenāsam) when you are familiar with a person, a place, or a thing. Since knowing something is magic is a fact, midānam is the right choice here.
Why is rā added after ān (it) near the end of the sentence?
The word rā marks a specific direct object—the thing that directly receives the action of the verb. In the phrase ān rā didam (I saw it), "it" refers to a specific thing you already mentioned (the magic). Because it is a specific object being seen, it must be followed by rā.
Since the verbs midānam and didam both end with the "I" suffix -am, do I really need the pronoun man at the start?
No, you don't! In Farsi, the verb ending tells us who is doing the action, so subject pronouns like (I) are optional. Including here just adds a bit of emphasis, as if saying "I myself know that this is magic."