Young children learn words best when they hear them repeatedly inside real, shared experiences, during conversations, play, stories and routines, and get the chance to use them; drilling isolated words on flashcards tends to produce recitation that does not carry over into everyday use. In a bilingual classroom, this means words in both languages are attached to things children are doing and thinking about, and teachers plan which words to build, not which cards to show.
This article explains what research tells us about how preschoolers learn words, from joint attention and fast mapping to the slower process of deepening meaning, why a bilingual child's vocabulary should be counted across both languages, how to choose words worth teaching, and how to plan the vocabulary of a theme so that it grows naturally in Vietnamese and English.
Why flashcard drills promise more than they deliver
Flashcards are attractive because they produce visible results quickly. A child shown a card of an apple twenty times will soon say "apple" when she sees it, and the moment can be filmed for families. But the skill being practised is narrow: matching a picture to a sound on cue. It says little about whether the child can use the word in a sentence, understand it in a story, recognise a real apple of a different colour, or ask for one at lunch.
Drills also miss the conditions in which children learn language most powerfully. A word on a card has no shared purpose, no emotional significance and no connection to anything the child is doing. Children are good at learning what matters to them right now, and a card rarely matters. The time spent drilling is time not spent in conversation, which is where vocabulary and grammar develop together.
None of this means pictures are useless. A picture card can be an excellent prop in a game, a support for a story, or a visual choice for a child who is not yet speaking. The difference lies in its purpose. Used to support meaningful communication, a picture helps. Used to drill a list for recall, it mostly teaches children to perform.
How preschoolers actually learn words
Research on early word learning highlights joint attention: the child and the adult attending to the same thing at the same time, with the adult naming or commenting on it. The developmental psychologist Michael Tomasello and others have shown how much infants and toddlers rely on social cues, such as where an adult is looking and what she seems to intend, to work out what a new word refers to. A teacher who names what a child is already looking at gives her the easiest possible word-learning moment.
In a well-known 1978 study, Susan Carey and Elsa Bartlett showed that preschoolers could form a rough idea of a new colour word, "chromium", from a single incidental exposure. This ability, often called fast mapping, explains how children's vocabularies can grow so quickly. But fast mapping produces only a first sketch. Full understanding, knowing the word's range, its links to other words and how to use it, develops slowly through many encounters in varied contexts.
The importance of live interaction was illustrated by Patricia Kuhl and colleagues in a 2003 study in which American infants of about nine months heard Mandarin from a live speaker over several sessions and retained the ability to distinguish a Mandarin sound contrast, while infants who heard the same material from video or audio recordings did not. Screens and recordings have their uses, but for young children, people talking with them about shared experiences remain the main engine of language learning.
Counting a bilingual child's vocabulary fairly
A bilingual child's vocabulary is split across two languages, and this has led to a persistent misunderstanding. If you count only her English words, or only her Vietnamese words, she may appear behind a monolingual peer. In a 1993 study, Barbara Zurer Pearson, Sylvia Fernández and D. Kimbrough Oller compared bilingual and monolingual toddlers and proposed counting total conceptual vocabulary: the number of concepts a child can name in at least one language. Measured this way, the bilingual children were comparable to their monolingual peers.
For teachers this has two implications. First, a bilingual child's English vocabulary at any moment is only part of what she knows, and should never be read alone as a measure of her language ability. Second, vocabulary in each language reflects the experiences she has had in that language. A child who cooks with her grandmother in Vietnamese and builds with blocks at school in English may have rich kitchen words in Vietnamese and rich construction words in English.
Good planning uses this rather than fighting it. When a theme introduces new concepts, teachers make sure the important ones are met in both languages over time, so that each child's conceptual vocabulary grows and her words in each language gradually cover more of what she knows.
Choosing words worth teaching
Not all words need the same attention. Isabel Beck, Margaret McKeown and Linda Kucan, in their book on robust vocabulary instruction, proposed thinking in three tiers. Tier one words are everyday words most children pick up through ordinary conversation, such as dog, run or happy. Tier two words are more sophisticated words that appear across many contexts and in books but less often in everyday speech, such as enormous, gentle, discover or delicious. Tier three words are specific to a field, such as photosynthesis.
The framework was developed for school-age children, but the idea adapts well to preschool. For a bilingual class, tier one words in the weaker language are the essential base: food, body parts, actions, feelings and classroom objects. Beyond that, the most valuable targets are often tier two words that carry ideas children are ready to think about: words like float, sink, heavy, empty, careful, curious, together. Field-specific words have a place when children are genuinely fascinated, a dinosaur-mad four-year-old will happily learn "herbivore", but they are not the core.
Feeling words deserve special attention in both languages. Children who can name frustration, disappointment, excitement and worry have more tools for managing them, and bilingual children benefit from having those words in the language of each relationship that matters to them.
Vietnamese words carry things English words do not
Vocabulary planning in a Vietnamese–English classroom has to respect how differently the two languages package meaning. Vietnamese is a tonal language, so the same syllable with a different tone is a different word, and children learning Vietnamese as a second language need to hear words many times in clear, natural speech to tune into tones. English-speaking teachers who try to model Vietnamese words should do so sparingly and accurately, leaving most Vietnamese modelling to fluent colleagues.
Vietnamese also uses classifiers, small words such as con, cái, quả or chiếc that come before many nouns depending on the kind of thing named, as in con mèo for a cat or quả cam for an orange. Children learn these through use rather than rules, and a teacher who models "hai quả cam" while counting real oranges is teaching number, classifier and noun at once. In English, by contrast, children have to master plural endings and articles, which Vietnamese does not mark in the same way.
These differences are a reason to plan vocabulary separately for each language rather than translating a single list. A word that is simple in one language may need a phrase or a different structure in the other, and the theme should give children chances to hear each language doing what it does naturally.
Everyday strategies that build vocabulary
Narrate and comment. Describe what the child is doing and what you are doing, using precise words: "You are stacking the cups, the tower is wobbling, it is leaning to one side."
Expand children's words. When a child says "car fast", reply "Yes, the car is going very fast down the ramp." The child hears her idea extended with richer vocabulary and grammar.
Explain new words in the moment. When a less familiar word comes up, add a short, child-friendly explanation: "This is enormous, that means very, very big."
Use objects and actions. Real objects, gestures and acting out a word help children, particularly those in the weaker language, link sound and meaning firmly.
Revisit in play. Put materials connected to new words into play areas so children meet and use the words again on their own terms.
Read the same book more than once. Repeated reading lets children notice new words, predict them and eventually use them; children often ask for the same story because they are still learning from it.
Planning the vocabulary of a theme in two languages
Vocabulary planning works best when it starts from the experience, not from a list. A practical sequence for a two-to-four-week theme looks like this.
- Plan the experiences first: what children will do, explore, cook, build, visit and read.
- List the words children will need to talk about those experiences, in Vietnamese and in English, including actions, descriptions and feeling words, not only nouns.
- Choose a small set of focus words in each language, typically a handful of everyday words and a few richer tier two words that carry the theme's big ideas.
- Decide where each focus word will be met first, in which language, and where it will be revisited in the other language later in the theme.
- Find or prepare books, songs, rhymes and play materials that use the focus words naturally.
- Observe and note which words children begin to use spontaneously, in which language, and adjust the plan for the next theme.
Keep the focus lists short enough that every adult in the room can remember them without looking. A teacher who knows the five English and five Vietnamese focus words of the week will weave them into talk all day, whereas a list of forty words on a planning sheet tends to be forgotten by Tuesday.
A worked example: a garden theme in two languages
Consider a class of four- and five-year-olds planting beans and leafy greens in the school garden over three weeks. The experiences come first: preparing soil, sowing seeds, watering, watching for shoots, measuring growth with string, and finally harvesting and cooking a simple dish. From these, the team draws its language. The everyday English focus might include soil, seed, water, grow, dig and leaf. The richer English focus might be sprout, root, gentle and compare. In Vietnamese, the focus might include đất, hạt, tưới, nảy mầm and rễ, plus feeling words for waiting and surprise.
Teachers decide that sowing and daily watering will be talked through mainly in Vietnamese, while the measuring and comparing activity is led in English. The concept of roots is introduced in Vietnamese when a seedling is gently lifted to look underneath, and revisited in English a few days later during a story about a growing plant. Books, a song about seeds and a play tray with soil, pots and scoops sit in the room throughout.
By the third week, teachers note children saying "it's sprouting" at the window and arguing in Vietnamese about whose bean is taller. Those notes, not a quiz, tell the team the vocabulary has taken root.
Câu hỏi thường gặp
Are flashcards bad for young children?
Not in themselves. Picture cards can be useful props in games or visual supports for a child who is not yet speaking. The problem is drilling isolated words for recall, which produces performance rather than words children can use in real communication.
How many times does a child need to hear a word to learn it?
There is no fixed number. Children can form a first idea of a word from one exposure, but full understanding develops through many encounters in varied, meaningful contexts. Repetition inside real activities, stories and play is what deepens it.
Why does my bilingual student seem to know fewer English words than monolingual peers?
Because her vocabulary is split across two languages. Research on total conceptual vocabulary suggests that when concepts known in either language are counted, bilingual children are generally comparable to monolingual peers. Her English reflects only part of what she knows.
Which words should a preschool focus on?
In the weaker language, essential everyday words come first. Beyond that, richer words that carry ideas children are ready for, such as float, gentle or discover, and feeling words in both languages, are especially valuable. Specialist words are welcome when children are interested.
Can screens and videos teach vocabulary to toddlers?
Research suggests that for infants and toddlers, live interaction is far more effective than recordings. Videos may support older children as one source among many, but conversation with responsive adults about shared experiences remains the main way vocabulary grows.
How do teachers know if vocabulary teaching is working?
By observing whether children use focus words spontaneously in play and conversation, understand them in stories and instructions, and begin using them in new contexts. Notes on these moments guide planning; children are not tested or compared.