Final answer:
To express an ongoing action in Spanish, use the present progressive by combining the verb 'estar' in the present tense with the gerund of the main verb.
Step-by-step explanation:
To rewrite the sentence 'Yo camino hacia la escuela' using the present progressive, you would say 'Yo estoy caminando hacia la escuela.' In Spanish, the present progressive is formed by using the verb 'estar' conjugated in the present tense followed by the gerund of the main verb. In this case, the gerund of 'caminar' is 'caminando.' This form indicates an ongoing action that is happening at the moment of speaking.
Learn more about Spanish verb conjugation