Parallel progression with "a medida que"
To describe two things changing or evolving at the same time, use a medida que (as / at the same time as).
When describing a habitual process or an ongoing fact, use the indicative mood for the verb following a medida que.
| The dough improves as we knead. | La masa mejora a medida que amasamos. |
| The sourdough starter grows as it ferments. | La masa madre crece a medida que fermenta. |
| The dough needs more water as you add the flour. | La masa necesita más agua a medida que añades la harina. |
Anticipated progression with the subjunctive
When using a medida que to talk about a process that will happen in the future, use the subjunctive mood.
This shows that the parallel progression is anticipated rather than already experienced. Notice how the main clause in these situations often uses a future structure like ir a + infinitive.
| We are going to see more bubbles as the dough ferments. | Vamos a ver más burbujas a medida que la masa fermente. |
| The crust is going to get dark as we bake the bread. | La corteza se va a poner oscura a medida que horneemos el pan. |
Starting the sentence with "a medida que"
You can also place the a medida que clause at the beginning of the sentence to emphasize the progression. Just use a comma to separate the two halves of the sentence.
The rules for choosing between the indicative and the subjunctive remain exactly the same regardless of word order.
| As the sourdough ferments, the bubble grows. | A medida que la masa madre fermenta, la burbuja crece. |
| As you knead the sourdough, it is going to be more elastic. | A medida que amases la masa madre, va a ser más elástica. |