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Monitoring Vocabulary Development in Children

By Jessica Hawkins, CEI Intern

The knowledge we have about the impact of early literacy on academic achievement has gotten parents and teachers alike interested in children’s vocabulary from a young age. Whether using clinical assessments or a parent’s curious observations, keeping track of a child’s vocabulary development is essential. After all, the knowledge anyone has about a subject is built on the understanding of the terminology of said topic. The current, most popular, and widely-used method for assessing the vocabulary of toddlers consists of a written form with several hundreds of items, which takes 45 minutes or longer to complete. Researchers Dr. Nivedita Mani and Dr. Julien Mayor have recently developed an easy and time-efficient way to monitor children’s vocabulary through a new app called BabyLex.

BabyLex: An App to Monitor Vocabulary Growth

The BabyLex is an app that provides an estimation of a child’s vocabulary size in just a few minutes. Specifically, BabyLex provides an approximation of the score obtained from the traditionally-used MacArthur-Bates Communicative Development Inventory (CDI). Parents and other adults, like a child’s preschool teacher, are asked to identify which words their children produce out of a list of 25 words. These words are randomly selected from WordBank, an open database containing data from over 70,000 CDI forms that matches words from children in a similar age, gender, and language group. When using Babylex, adults have access to:

  1. a percentile score showing how the child compares to similar children in their age group

  2. an estimated number of words that the child produces

  3. options to add multiple children

  4. functions to save results over time to track development

  5. multiple retests without compromising reliability or validity (Mayor and Mani, 2018).

Benefits of BabyLex over Traditional Measures

BabyLex has several features that make it attractive to parents and teachers. Mayor and Mani (2018) point out that even 25 words selected in a method similar to BabyLex show high validity and reliability. Moreover, the number of words a child produces also predicts the ability to learn to read (Lervåg & Aukrust, 2010). Vocabulary shapes the way children conceptualize and experience the world around them. Until recently, the only way for adults to monitor the development of vocabulary in toddlers has been through filling out long forms, such as the CDI which has limitations including the following.

  1. These forms have limited use in clinical settings and with multilingual children or parents with low literacy (Mayor & Mani, 2018).

  2. For clinicians who use multiple tests, vocabulary testing can take up valuable time and resources.

  3. For multilingual households, the forms and time must be multiplied by the number of languages spoken.

  4. For parents with low literacy levels, the entirety of the form could be difficult to complete. This difficulty in monitoring vocabulary development for these parents is especially harmful because of the “million word gap” which separates children whose parents rarely read to them from children with parents that read to them every day.

Giving parents or teachers an idea of a child’s vocabulary early enough could allow for better school-based interventions for these children.

Vocabulary Development

If you believe a child’s vocabulary development is lacking, there are several ways to help. In addition to reading, talking to pre-verbal children and engaging verbal children in conversation builds a strong vocabulary. Singing, rhymes, and poetry can also help a child learn valuable vocabulary skills. If the child seems to require additional help, families should visit their pediatrician to rule out any type of biological hindrances, such as hearing problems. Pediatricians or schools should be able to provide references to a speech-language therapist. In addition, each state has an early intervention services office, which should provide free full evaluations.

Monitoring Vocabulary in Multiple Languages

Currently, BabyLex is available for English-speaking children ages 16 to 39 months, German-speaking children ages 18 to 30 months, and Norwegian-speaking children ages 18 to 36 months. While this app makes assessing multiple languages easier than the CDI, BabyLex does not yet offer Spanish-language or Mandarin assessments, two of the most widely spoken languages in the world. Although the app only allows for a few languages, the full-length CDI provides adaptations for several languages, including sign language for multiple dialects.

It is beneficial for parents and teachers to monitor the vocabulary of young children. This may be particularly important for toddlers who may have developmental delays. Early intervention, including speech and literacy interventions at an early age, can not only provide needed support to accelerate a child’s learning, it can make the transition to school and the path to school readiness easier. BabyLex is available for free for both Android and iOS devices.


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