Explanation in Plain Language
Veins are very small tubes inside our body. A vein takes blood to our heart.
Words with same meanings
Inside our bodies are lots of different sorts of tubes.
There are some very thin tubes that move things our body needs to different places in our body.
Some thin tubes move blood. Blood is the red stuff you see if you cut yourself. It is pushed round our body by our heart.
The thin tubes that move blood back to our heart are called veins.