This will require more thorough testing of the user-creation API, but the endpoint expects a nested JSON representation of the user, including school. So, the data we send to the server needs to look more like:

```javascript
first_name: this.state.first_name,
last_name: this.state.last_name,
...
school: {
  name: this.state.school_name,
  address: this.state.school_address,
  ...
}
```