Question: Can you tell Entity Framework to add an extra field for each field of a certain type? For example: Is it possible to generate a ChangedAt datetime field for each boolean field defined in the model, so this

```
public bool Confirmed { get; set; }

```

could result in a table with an additional field `ConfirmedChangedAt` where the value is updated each time the boolean value is changed.

Answer: 
I think if i understand you correctly, You are expecting the Entity Framework to be able to add columns to the database automatically so that you don't have to add them manually, Well you have 2 cases:

1. if you are using the database first approach you could achieve this
by using a query that's specific to your needs to add these columns
for you based on the conditions you have.
2. If you are using the code first approach and you have an existing database you may reverse engineer the database using the Entity Framework Power Tools and you could customize the T4 Templates to generate the entities with the extra properties that you need.
Plain answer no. 
But it's depend on way how you interact with EF (code first, model first,database first). 
If you using EF 6 and code first approach you can use idea of base Entity class

```
public class BaseEntity
{
    public DateTime ChangedAt {get;set;}
}

public class ConcreteEntity : BaseEntity
{
    public string Name {get;set;}
}

```

Now ConcreteEntity has ChangedAt by inheritance.
If this solution not for you, please explain question with more details.