This is a question many signing parents put out when they first begin on the baby signing journey. To answer it, you’ll have to ask yourself how many signs you’re willing to teach, because eventually, your baby will learn each and every one of those!
Every baby can learn all of the signs. However, not all babies will learn them as fast as other babies. For example, my son picked up over 150 signs well before his 20 month mark. He might have stopped at 100 or even 50, but his parents didn’t give up. As his interests developed and his world expanded, so did his desire to pick up signs. We just kept adding more. The fact of the matter is that babies are like sponges, soaking up everything that is happening around them, so if signing is one of those things, then your baby will pick this up too.
Most parents will stop at around 20 or so signs. This might be because the honeymoon phase has warn off and signing takes a backburner to other more pressing issues and stresses. Perhaps Mom has to go back to work or Dad isn’t as interested as he was before in helping. Some parents have lots of help from family – Grandparents, and other have help from older siblings. These are all factors in how many signs your baby will learn.
Once you reach a certain threshold your baby begins to understand the rules of signing and starts to pick things up in what seems like an instant. I’ve been able to teach my 19 month old a sign in about 5 minutes and yet other times I think he’s not paying attention, but when I quiz him later on, he repeats the lesson (and sign) back to me! Here I was thinking he was playing with his trucks when all along he was dividing his attention. So while early learning might seem like hard work, rest assured, that later signing will become second nature.
The bottom line is that if you want your baby to sign over 100 words, he will. With only rare exception it’s completely up to you!