Here's how I like to think of language development: It's like a ladder. All children are on this ladder somewhere, even if it's just briefly, and there's things we can do to help them move to the next step.
The important thing here is that we always MODEL THE NEXT STEP UP. If our child says "wow!" and we say "wow!" back to them, we've missed a great teaching opportunity and our child hasn't learnt anything new. If instead we modelled one step up on the ladder and said "wow a plane!" Then we've poured in more language and your child is more likely to use that language if the same situation arises again.
So should you always just talk one rung above?! babble all day?!
It's still important that our children hear us talk in full sentences (we're all at the top of the ladder). Narrate your day and talk them through what you're doing. But in RESPONSE to your child's communication attempts or in TEACHING moments during play, be mindful that you're always one step ahead and not modelling anything too complex. If your child said "wow!" And you said "that's a fascinating display of excellent aviation" (😂) you can see why they're less likely to learn from that!
Your child is already on 2 steps of this ladder. WHATTTT?!!
That's because a child's UNDERSTANDING of language develops faster than THEIR EXPRESSIVE language.
MAP YOUR CHILD. Think about where your child is right now. E.g. They might be at the babbling and cooing stage expressively but understand short phrases like "get your shoes", "where's daddy?". Now you have a BASELINE of where your baby is at, you can model language appropriately. You can also reflect back if in a few months you haven't seen much change in their development.
Where is your baby on the language development ladder?