A vocabulary spurt is a point in which a child may display a sudden growth in their spoken vocabulary. This occurs when a child switches from early language learning of approximately two words per week per week to suddenly acquiring and using around 20 new words per week. This does not happen in all children (only approximately 1 in 5) with most children acquiring vocabulary at a steady but increasing rate between 12 months and seven years. Most children start using single words at around 12 months. Between 18 and 24 months they start combining words to express ideas and feelings such as "no bye-bye" or "want Teddy."