1. i learned that friction is the force that happens when 2 surfaces rub together, like a block and sandpaper.you can measure friction in many ways, including newtons and LBS.
on narrower sides, theres more weight since its a smaller side, so its harder to pull, which means there's more friction.
2.we measured friction by pulling the block with a little scale thing, and it measured the force it takes to pull it with newtons by feeling the drag the block creates.
3. controlled variables are the thing that when you do several experiments, it stays the same. we controlled: pulling speed,pulling length, and block type.