In the following sentence, should i say "it" or "they?" (becuase i put the word "each" and it is plural).

"...then count the number of weights each wood held before it sank."

I don't understand the sentence. What do you mean by "each wood held?"

What sank?

the wood sank.

that was just part of a sentence.

Each wood held metal weights (40 grams)

If the wood sank, then use "it."

Each is singular, as is wood.

In this sentence, "each" indicates that multiple woods are being referred to, so the pronoun should match the plural noun. Therefore, you should use "they" instead of "it." To determine this, you can break down the sentence and identify the subject and its corresponding pronoun.

Subject: "the number of weights each wood held"
Pronoun: "they"

By recognizing that "each wood" is the subject and that it is plural (implied by the word "each" indicating multiple woods), you can conclude that the correct pronoun to use is "they."