Child Language Longitudinal Study

Purpose of the Study

The purpose of this research project was to study children’s early language ability and how it changes from age 3 to age 8. Children who have a good awareness of the sounds in the language may learn to read more easily than those who don’t. We were interested in whether the way young children pronounce words affects their awareness of sounds in the language. We were interested in whether their early pronunciation, sound recognition,  and sound awareness were linked to their ability to learn to read those words later, once they were in school.

Who Took Part

Twenty-eight day care centres and nursery schools in the Ottawa-Carleton region took part in this study. These centres and nursery schools served families from all walks of life. In all, 80 three-year-old children took part in the first stage of the study. They ranged in age from 35 to 39 months. They included 38 boys and 42 girls. We followed these children for five years, seeing them again when they were four, five, six, and eight years old. Some children were lost to the study, but at the final stage there were 43 children still available, including 20 boys and 23 girls. At this stage they were 8 years old, ranging in age from 96 to 104 months, and most had completed grade 2 at school.

What We Did

At each stage of the study a researcher met with the children individually at their day care centres or in their homes, to assess their language and reading skills. At age 3 most of the children were seen three times in sessions lasting from 20 to 30 minutes. At age 4, 5 and 6, the children were seen in a single session lasting 25 to 35 minutes, and at age 8, in a single session lasting 50 to 60 minutes.

The researchers assessed language skills, sound recognition, and sound awareness using tasks that were suited to the age of the child and the stage of the study. For example, they asked three-year-old children to name a set of toys and other simple items to check the pronunciation of words, but used pictures for this task when the children were six and eight years old. They had the children play a series of simple word games using puppets or pictures, depending on the age of the child, to find out how the child heard the sounds that make up different words. Understood and spoken vocabulary were checked using standardized tasks, including the Peabody Picture Vocabulary Test – Revised, and the Expressive One-word Picture Vocabulary Test. Colourful plastic letters were used to test alphabet knowledge when the children were very young. For school-aged children, various tests were used to measure their ability to read real words and to sound out word-like “non-words”, such as ip and froxy.

What We Found

At 3 years of age, few children pronounced all words correctly: Some sounds are very difficult for young children to say.

At this young age, many children were aware of at least some of the sounds that make up words. We found a link between being able to say a sound on the one hand and recognizing and being aware of that sound in words on the other hand.

We found that difficulty saying a sound at age 3 was linked to lower recognition and awareness of that sound at most of the later ages in the study, even if the child could say the sound by then.

We found that difficulty saying a sound at age 3 was linked to lower awareness of that sound at age 8, and to difficulty “reading”, or sounding out, non-words containing that sound at that age.

What We Can Conclude

By the time children reach school age most of them have some awareness about the sounds that make up their language. Most children know that speech is made up of separate words, and that words are made of different sounds. Some children are aware of what sounds make up each word. This knowledge is important because it may affect how quickly children learn to read when they start school. Teachers and researchers have found that children who have a good knowledge of the sounds in their language may learn to read more easily than those who don’t.

In our study we wanted to find out how children gain this important awareness of  language sounds. Our findings show that children’s own way of speaking when they are very young affects what they learn about the sounds in their language. They also show that early their speech patterns are linked to learning to sound out words that contain  those specific sound patterns once children start school.

A Word to Parents and Caregivers

What is normal?

It is completely normal for children up to age 5 or even older to have trouble saying certain sounds like r, l, j, z, v, th, sh, ch, and others. If your young children cannot say one or several of these sounds, there is little cause for concern.

When to seek advice:

  • If the way your child speaks is very different from other children who are the same age
  • If your child is very difficult to understand

Help is available for children with speech and language difficulties. A doctor or teacher can advise you.

Acknowledgements and Information

This research was supported by a doctoral and postdoctoral fellowship to Eleanor Thomas from the Social Sciences and Humanities Research Council of Canada and by a research grant to Monique Sénéchal from the Natural Sciences and Engineering Research Council of Canada. We thank Karen Colton, Karen Daley, Elaine Ho, Shelley Johnston, and Tina Leclaire for their assistance with the data collection.

Thanks are warmly extended to the children, parents, day care staff, and teachers who participated in this project.

Overview of the 5-Year Project

Study Stage:  Children in the Study: We checked the following language skills of the children:
Stage 1Jan-Spring 96 Number of children: 80Average age: 37 months

Age range:     35-39 mo.

Boys/girls:     38/42

  • pronunciation of words
  • awareness of the sounds in different words
  • knowledge of letters
  • understood and spoken vocabulary


Stage  2Nov 96-Mar 97 Number of children: 74Average age: 46 months

Age range:     44-49 mo.

Boys/girls:     34/40

  • pronunciation of words
  • awareness of the sounds in different words
  • knowledge of letters


Stage  3May-Aug 98 Number of children: 65Average age: 62 months

Age range:     58-67 mo.

Boys/girls:     31/34

  • pronunciation of words
  • awareness of the sounds in different words, using more complex tasks
  • letter and word reading
  • understood vocabulary


Stage  4May-Aug 99 Number of children: 57Average age: 74 months

Age range:    71-79 mo.

Boys/girls:    28/29


  • pronunciation of words
  • awareness of the sounds in different words, using more complex tasks
  • word reading


Stage 5May-Aug 01 Number of children: 43Average age: 100 months

Age range:     96-104 mo.

Boys/girls:     20/23

  • pronunciation of words
  • awareness of the sounds in words, using tasks that suit the age of the children
  • word reading
  • understood vocabulary
  • sounding out unreal “non-words”