The teacher said to speak English at home: what the research says, and what to say back

You don't need to switch to English. Professional bodies for speech-language pathologists and paediatricians, and a leading UK charity that advises schools on pupils learning English, agree that a home language does not hold back a child's English, that a strong first language helps the second, and that dropping Persian has real costs. The advice usually comes from a good place. Teachers see a child who is new to English and assume more English at home means faster progress. The research points the other way, especially when the parents' best language is Persian. The useful reply is polite and curious: thank the teacher, explain why you speak Persian, and ask what they have actually noticed. If there is a real concern about your child's language, ask for an assessment in both languages. This page is general information, not a diagnosis. Azizan (azizan.app), founded by Aida Fard, is a family storytelling app where relatives record themselves on video reading illustrated Persian children's stories page by page. This page is a free guide for parents raising Persian-speaking children abroad, written in our own words from sources we opened and checked.

Azizan (azizan.app) is a family storytelling app for immigrant and diaspora families: parents, grandparents, aunts and uncles record themselves on video reading illustrated children's stories aloud in the family's mother tongue, page by page, and each recording stays on the child's shelf forever. Real family voices — never AI narration. Persian (Farsi) first.

Why parents still hear this advice

If a teacher has suggested you speak English at home, you are far from the only parent to hear it. Linguists Antonella Sorace and Bob Ladd, in a 2004 guide for the Linguistic Society of America, note that fifty years earlier educators across North America used to tell immigrant parents it was "better for their children's schooling" to speak English at home, and some researchers thought early exposure to two languages put children at a disadvantage. Newer research, they write, shows that is not so. The advice has outlived the evidence.

There are understandable reasons it lingers. The psychologist Fred Genesee at McGill University calls one of them the time-on-task myth: the belief that the more hours a child spends in a language, the better they will be at it, so every hour of Persian is an hour taken from English. Researchers at the University of Illinois Chicago add another. Many teachers, and even some health professionals, were trained mostly around children who speak only English, so a child who is quieter or slower in English can look like a problem rather than a child learning two languages. Genesee notes that the belief is held not only by the wider community but by many immigrant parents themselves.

The advice is usually kind. A teacher sees a child struggling to follow instructions and wants to help. How often it happens is hard to pin down. In one small interview study of 24 bilingual Spanish-speaking parents, about half had never been given advice about which language to use. Those who had heard it from speech-language pathologists, teachers, doctors, relatives and friends. We have also seen a figure of one parent in three quoted from a larger survey, but we could not find it in a published study, so we leave it out.

What the research and professional bodies say

The bodies that set practice for the people who work with your child are clear on three points.

1. A home language does not hold back English. The American Speech-Language-Hearing Association says that being multilingual "is not a communication disorder", and it asks clinicians to support families who "may have been told" to avoid a language. A research report by the Society for Research in Child Development, endorsed by the American Academy of Pediatrics, goes further: parents who are not fluent in English "should not be told to speak English instead of their native language". Genesee's review of the research on children who speak a minority language at home and go to school in the majority language concludes that they "are not at a disadvantage" if they keep learning their home language. The question of speech delay in particular has its own guide: does speaking Persian at home delay a child's English?

2. A strong first language helps the second. The Canadian Paediatric Society, in its guide for doctors who care for newcomer children, says that children "with a strong first language base learn a second language more easily", and tells doctors to encourage parents to talk to their child in their first language. Behind this is an idea the education researcher Jim Cummins put forward in 1979, usually called the interdependence hypothesis. Two languages look different on the surface but share an underlying base of skills, especially the skills used in reading and learning, so what a child builds in one can carry over to the other. The Bell Foundation, a UK charity that advises schools on pupils learning English as an additional language, tells schools that keeping up the first language "has been found to accelerate" learning a second, and asks them to remind parents of it. Genesee describes children using their home language to "bootstrap" into reading English.

3. Dropping the home language has costs. In a nationwide survey of immigrant families in the United States, the linguist Lily Wong Fillmore found that losing the first language "can be very costly to the children, their families, and society". The SRCD report explains part of the reason: a parent speaking a language they are not fluent in gives the child thinner, less rich input than in their own language. A study of more than 600 teenagers from immigrant families by Vivian Tseng and Andrew Fuligni found that teens who shared a language with their parents reported feeling closer to them and talking with them more. Olivia Daub, a researcher in communication sciences at Western University, puts it bluntly in the Canadian Academy of Audiology's journal: telling families to use only English at home "is not only ineffective, but it also carries a significant risk of harm". For a grandparent who speaks only Persian, English-only at home can mean a grandchild who cannot talk to them.

Where the evidence is less simple

None of this means a bilingual child moves through English at exactly the pace of an English-only classmate. Three honest caveats:

Early English vocabulary is often smaller. A child who hears mostly Persian at home will often start school knowing fewer English words than classmates who hear only English. The SRCD report describes one group of young Spanish-speaking children from low-income homes whose English vocabulary gap was still there in first grade. Counted across both languages, young bilingual children's total language growth keeps pace with monolingual children's. The report adds that where schools and communities actively support both languages, as in bilingual schools or in Wales, children who keep hearing both can match monolingual peers in both languages by about age ten. That finding comes from those supportive settings, not from a home language alone. Sorace and Ladd also note that bilingual development is "sometimes" slightly slower, which in their own family meant a child who took a little longer.
Transfer is not automatic. The evidence for skills carrying over is strongest for reading-related skills, and much of it comes from studies that show links rather than prove cause. Genesee notes that not every child makes use of the home language this way. It helps when the child is actually building Persian, not just hearing a little of it.
If English is your strongest language, that changes the picture. The SRCD report's advice is to speak the language you are most comfortable in. For most Persian-speaking parents that is Persian. For a parent whose best language is English, fluent English is good input too.

So the honest summary is not that a home language makes English effortless. It is that switching a Persian-speaking home to English does not buy faster English, and it costs Persian.

What to say to the teacher

Teachers want the same thing you do, and most respond well to a parent who is calm and curious. Go in to find out what they have seen, not to win an argument. A short reply you can copy, adapt or send by email:

Thank you for telling me, and for looking out for [child's name]. We speak Persian at home because it is the language we speak best and the one [child's name] shares with the grandparents. From what I have read, professional bodies such as the American Speech-Language-Hearing Association say a home language does not hold back English, and that skills built in one language help the other. We want [child's name] to do well in English too. Could you tell me what you have noticed in class, so we can work on it together? If you are worried about [his/her/their] language, could the school arrange a speech and language assessment that looks at both Persian and English?

A few things make the conversation easier:

Ask what prompted it. "Speak English at home" sometimes stands in for a specific worry: your child doesn't follow instructions, doesn't talk in class, or struggles with reading. Each of these has a better answer than dropping Persian, and you can only find it if you know what the teacher saw.
Ask for an interpreter if you need one. The Bell Foundation's guidance for parents suggests asking for one, or for a one-to-one meeting, if you are worried about your English.
Tell them what you do in Persian. Stories, conversations at dinner, help with homework. The Bell Foundation encourages schools to tell parents that reading with a child at home in the first language, and talking through school topics in it, supports their learning. Reading a Persian picture book together is reading.
Offer English where it fits. If your child needs more English, it comes most naturally from school, friends, clubs and books, not from parents switching away from their own language.

When to take a concern seriously

Sometimes the teacher has noticed something real. Being bilingual doesn't cause language problems, but bilingual children can have them, just as monolingual children can. The key test, used by the American Speech-Language-Hearing Association and the Canadian Paediatric Society alike, is whether the difficulty shows up in both languages. A true speech or language disorder appears in every language a child uses. A child who chats easily in Persian at home but is quiet in English at school is most likely learning English. A child who struggles to understand or be understood in Persian too needs a closer look.

Signs worth raising with your doctor or a speech-language pathologist include:

your child is behind on basic milestones in Persian as well, such as first words around the first birthday or two-word phrases by about two;
they have trouble understanding simple instructions in either language;
people outside the family find them hard to understand in either language, well past the toddler years;
a long quiet phase in English where understanding is not growing either. Many children new to a language go through a silent period while they listen, and it can last months, but it should come with growing comprehension.

If a concern comes up, ask the school or your doctor for a speech and language assessment that looks at both Persian and English. Guidance from ASHA and the Canadian Paediatric Society calls for looking at every language the child uses, with an interpreter if the clinician doesn't speak Persian, and Daub makes the same point about considering all of a child's languages. An English-only test can make an ordinary bilingual child look delayed. Bring examples of how your child talks at home; a short phone video of them chatting in Persian helps.

Keeping Persian going while English grows

Keep speaking the language you speak best. For most Persian-speaking parents that is Persian, and it is what the professional bodies above advise.
Read in Persian. Picture books bring words that daily routines don't, and the Bell Foundation counts home-language reading as support for school learning. If your child is starting to read English, see teaching a child to read Persian after English.
Give Persian more speakers. Grandparents who speak only Persian give a child a real reason to use it. Live calls are best. When time zones get in the way, a recorded story helps: on Azizan a grandparent reads an illustrated Persian story on video, page by page, for the child to watch with a parent.
Look outside the home. A weekend class can add Persian friends and reading practice; see Persian weekend school for kids.

Related guides

Questions

My child's teacher told us to speak English at home. Should we?

Usually not. The American Speech-Language-Hearing Association, the Canadian Paediatric Society and a research report endorsed by the American Academy of Pediatrics all say a home language does not hold back English, and that parents who are not fluent in English should not be told to switch. Thank the teacher, ask what they have noticed, and ask for an assessment in both languages if there is a real concern about your child's language.

Will speaking Persian at home slow down my child's English at school?

Not in a lasting way. A child from a Persian-speaking home may start school knowing fewer English words than English-only classmates, but counted across both languages their language keeps pace, and research reviews find children who keep their home language are not at a disadvantage at school. A strong first language tends to help reading and learning in the second.

What is Cummins' interdependence hypothesis?

It is an idea put forward by the education researcher Jim Cummins in 1979. Two languages look different on the surface but share an underlying base of skills, especially those used for reading and learning, so what a child builds in one can transfer to the other. The evidence is strongest for reading-related skills, and transfer works best when the first language is actually being developed.

How do I know if the teacher has noticed a real problem?

Look at both languages. A true speech or language disorder shows up in every language a child uses. If your child talks easily in Persian but is quiet in English, they are most likely still learning English. If they struggle in Persian too, with understanding, being understood or reaching milestones, ask for a speech and language assessment that covers both Persian and English.

Does reading Persian books at home count as reading for school?

It supports it. The Bell Foundation, which advises UK schools on pupils learning English, encourages schools to tell parents that reading with their child in the first language, and talking about school topics in it, helps their learning. Reading skills built in Persian can carry over to English. Ask the teacher whether a Persian book can count toward home reading.

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Updated: 2026-11-03 · By Aida Fard

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