Parents
Read with them, read to them, listen to them reading in any language.
Encourage curiosity
Applaud effort
Develop positive study skills
Become involved at school
Take advantage of tech in Spanish
Watch quality shows designed for native-speaking but very young children
Play games that are focused on the communicative use of vocabulary & structures but don’t flood you with ads
Communicate with teachers
Intentionally visit places with high traffic from Spanish speakers, and attend cultural events
More ideas and details in this article Eight Ways to Support Your Children in Language Immersion
Check the AAPPL benchmarks from the state here: