Thank You Heidi in Port Orchard for this tip:

Whenever you know that your child has been learning a lot of vocabulary on a specific topic, make sure to go over the same topic in your language so that they will receive balanced vocabulary.

This is true whether the vocabulary was covered in school, at the playground, with the other parent, with grandma and grandpa or while playing with other children.

It can feel like too much to cover but don't worry, you have time! Get a notebook and keep notes of topics you'd like to discuss with your child. Review the list every now and then and see if something lends itself for discussion. Or maybe you already discussed a topic without remembering? If so, mark it off your list.

You shouldn't feel overwhelmed by this tip. Just keep it in mind. Most children who grew up in bilingual housholds comment on how separate their vocabularies were growing up: they knew certain subjects only in their mother's language and other subjects only in their father's.

Of course, no one is suggesting you take up a course in biotechnology or auto mechanics! It wouldn't hurt though, right? ;-)