Studies show that even up into middle school, measurement misconceptions are rampant. For years I thought my kids understood how to use rulers. It wasn't until the past three or four years that I discovered the misconceptions. They're easily hidden unless we dig a little deeper.
I've been working on fixing the issue. I've shared some strategies I'm trying on previous posts. Read about one of those strategies here. After you do, what I'm sharing below will make more sense.
Here are some additional opportunities for kids to practice measuring when the object is not lined up at zero. What if we move the zero to another spot on the ruler? Can they still measure that object? If so, they understand how a ruler and units work.