Learn Farsi: من باید به خودم بفهمانم که این بچه گرسنه نیست. - I must make myself understand that this child is not hungry.

This is a causative verb created from فهمیدن (to understand). To make a verb causative, you take its present stem, which is فهم, and add the infix ان. This creates the new causative stem فهمان. The full infinitive is فهماندن (to make understand). Here, it has the م ending for "I".

Why does بفهمانم start with a ب?

The verb follows باید (must). When a verb follows a modal word like باید, it must be in the subjunctive mood. You form the present subjunctive by adding the prefix ب to the verb. That is why the base form فهمانم gets the prefix to become بفهمانم.

Why do we use the preposition به before خودم?

In English, we say "make myself understand," but the Farsi verb فهماندن requires an indirect object. It literally acts like "to cause understanding to someone." Therefore, you must use the preposition به (to) before the receiver. Since خودم means "myself," به خودم translates to "to myself."

Can we drop که from this sentence like we often drop "that" in English?