# free module changes dimensions after base change

Hi, I have a free module of rank 1 over the integers

```
sage: M
Free module of degree 1 and rank 1 over Integer Ring
Echelon basis matrix:
[2]
```

However, when I base change it to the field with two elements, it changes dimension!

```
sage: M.change_ring(GF(2))
Vector space of degree 1 and dimension 0 over Finite Field of size 2
Basis matrix:
[]
```

What's going on?

P.S.: What does Sage mean by "degree"?