Learn Dutch: Zij giet het mengsel door de trechter. - She pours the mixture through the funnel.

Because she is actively pouring a direct object (a transitive action), it uses hebben: Zij heeft het mengsel door de trechter gegoten. The verb gieten (to pour) requires an object, so it does not alternate with zijn the way a verb like smelten (to melt) does.

How would we describe the mixture flowing through the funnel on its own to practice using "zijn"?

If you use an intransitive verb of motion to describe the mixture's own movement, like stromen (to flow), you would use zijn because it indicates a change of position. For example: Het mengsel is door de trechter gestroomd. This shows the contrast between a transitive action (hebben) and an intransitive event (zijn).

What are the past tense forms of gieten?

Gieten is a strong verb. The simple past is goot (plural goten) and the past participle is gegoten. If we wrote this sentence in the simple past, it would be: Zij goot het mengsel door de trechter.

Is there a rule to remember the gender of the word mengsel?