Determining Language Dominance: Why It's Important & How to Measure It

We already know that bilingualism is not static and it exists on a continuum in which one's proficiency is constantly changing over time. In some cases, bilingual people might be more dominant in one language when compared to the other (this is perfectly normal). As speech language pathologists, we need to be able to determine exactly where our bilingual student falls on the bilingual continuum by measuring the his/her language dominance in both languages. Why is this important and how do we do this you may ask? I will answer your questions down below: 

The Importance of Measuring Language Experience & Dominance

1. Measuring the student's language experience and dominance will allow you to make decisions about which language to evaluate in. Yes, we know that best practice indicates that we should always evaluate a bilingual student in both languages. However, in some cases, you might find that the student is actually exposed to one language significantly more than the other and he/she might present as a functional monolingual (receives input and output in one language more than 80% of the time). In those cases you might be able to avoid a lengthy evaluation process by only evaluating one language and possibly performing some informal tasks in the second language (if necessary). 
2. Measuring the student's language experience and dominance will allow you to make decisions about the types of supports that need to be provided in school. Perhaps after finding out that your student is exposed to and uses Mandarin 90% of the time at home, you will be able to advocate for your student and push for him/her to receive bilingual support at school. Your data will justify any decisions moving forward about bilingual placement, bilingual supports, etc. 
3. Measuring the student's language experience and dominance will allow you to make decisions about the language of intervention going forward. As mentioned, in some cases, a bilingual student may be more dominant in the majority language (English). I have come across cases where the caregivers indicate that the student is exposed to another language but after completing the language history questionnaire, and measuring the student's input and output of the language, I find out that the student is only receiving exposure to the other language 4% of the time and uses the second language 0% of the time. In those cases, I definitely want to proceed with English only intervention. 

How do I Measure a Bilingual Student's Language Experience & Dominance in Both Languages? 

The best way to measure a bilingual student's language experience and dominance in both languages is by collecting an in-depth language history. The language history will allow you to gain an understanding of the student's use and exposure of both languages. You can obtain an exact percentage of the student's language use and exposure in both languages by determining who the child lives with, their relationship to the child, the languages spoken and heard by the child each hour of the day. Once you have all the information over a week's span, you can calculate the average percentage of use and exposure of both languages. There is an exact formula that you can follow to obtain the percentages. I created a visual chart, formula document with step-by-step instructions and data organization chart which is available for free download in the freebie library (click here for formula and chart). It will walk you through exactly through the formula. Once you have this information, you will be able to see exactly where your student falls on the continuum and mention it in your report.

Based on the information, you should be able to figure out whether your student is a functional monolingual English (FME), functional monolingual other (FMO), bilingual English Dominant (BED), balanced bilingual (BL), bilingual other dominant (BOD), or functional monolingual other (FMO). Remember, a bilingual evaluation is always needed for BED, BL, and BOD students. So where do your students fall on the continuum?