Threw and through sound alike, but they do very different jobs in a sentence.
Threw is the past tense of throw. Use it when someone tossed, launched, or sent something. Example: She threw the keys onto the table.
Through is usually a preposition or adverb. It describes movement from one side to the other, passage within something, or completion from beginning to end. Example: We walked through the park after lunch.
- Use threw for an action done in the past.
- Use through for movement, passage, or completion.
- Quick contrast: He threw the ball through the window.
That contrast sentence helps show the difference clearly. Threw names the action. Through names the direction or path. If you can replace the word with tossed, you probably need threw. If you mean from one side to the other or all the way to the end, you probably need through.