Second Grade
Worksheets
Blood
Caption from left to right: a red blood cell, a platelet, and a white blood cell
You may have heard someone say that he is related to you or to another person by blood. You may be someone's blood brother. Sometimes people say that there is bad blood between them. Your grandfather might have said, "Blood is thicker than water." People who say these things are talking about families. The word "blood" has been used in many ways to talk about very important bonds. So what makes blood so important?
There are three parts to the circulatory system: the heart, blood vessels, and blood. Blood has many jobs to do in the body.
            1. It carries oxygen to the cells of the body.
