The Egyptians built the pyramids out of giant stone blocks that weigh several thousand kilograms each.
Weigh or weighs, which one is correct?
Some teacher give the following answer
The Egyptians built the pyramids out of giant stone blocks that weighs several thousand kilograms each.
The Egyptians built the pyramids out of stone blocks. Each block weighs several thousand kilograms. The blocks in the sentence is the plural form of block, not a singular word.
Let's not talk about whether "weigh" is appropriate here.
My confusion is that since the verb that follows the relative pronoun must agree in number with the word that comes immediately before the relative pronoun, if "blocks" are plural, then it must use "weigh" which contradicts with "each".
So, I guess "blocks" is a separate word, other than a plural form of block. I checked some online dictionaries and some of them support my view.
Could a kind professional on this area give an answer on this questions? Your clarification is very much appreciated!