Duolingo vs Lingokids vs Small Universe: Which Kids English App Actually Keeps Kids Learning?

Quick answer: For children learning English as a second language, we pick Small Universe, our own app: it is free, maps each planet to a CEFR level, and has 17 game types against Duolingo's 3-4 core mechanics. Duolingo ABC (free, ages 3-6) suits native speakers learning to read, and Lingokids suits under-5s who want several subjects.

The cheapest app might be the most expensive decision you make this year.

The price tag is the small part. The real cost is the hours your child spends on an app they quietly stop opening after two weeks, and the English words that never quite stick. By the time you notice, a season of learning has gone, and you can't get it back.

Here's a number that should bother any parent shopping for a language app. The average educational app has a 2% retention rate at Day 30. Out of every 100 people who download a learning app, only about two are still using it a month later. The other 98 have moved on, and when it's a child's app, the parents are left wondering what went wrong.

Almost always, the reason is the same. The app got boring.

We compared the three most talked-about kids English apps side by side: Duolingo (plus its younger sibling, Duolingo ABC), Lingokids, and Small Universe. We looked at age range, game variety, curriculum and CEFR mapping, price, ads and safety. Here's how they compare.

Quick comparison table

Look at the game types row. That gap matters more than it seems, and we'll get to why below.

Age range and who each app is actually for

Duolingo ABC (ages 3-6)

Duolingo ABC is a solid phonics and early reading app for native English speakers, aimed at ages 3-6 (pre-K to 2nd grade). It teaches the alphabet, letter sounds, sight words, and beginning reading skills across 700+ lessons. It's well-made and completely free.

Many parents miss one detail. Duolingo ABC teaches kids to read English. It doesn't teach kids to speak English. If your child already speaks English at home and needs help with reading readiness, ABC is a fine choice. If your child is learning English as a second or additional language, ABC skips the vocabulary and comprehension foundation they need first.

The main Duolingo app is built for a general audience (teens and adults). Children under 13 can use it through a parent-email account with limited social features, but everything about it, down to the pace of the lessons, is pitched at older learners.

Lingokids (ages 2-8)

Lingokids starts the youngest, at age 2. It mixes English with math, science, arts, and social-emotional learning. Its English content from Oxford University Press gives it academic credibility.

That breadth is the appeal, and also the limit. Lingokids is good at exposing young children to English through songs, games, and stories. But because it spreads across so many subjects, the English progression is less structured than in a dedicated language app. There's no clear path from beginner to intermediate.

Best fit: Toddlers and preschoolers (2-5) who need general early learning exposure with some English mixed in.

Small Universe (age 3 and up)

Small Universe has no upper age limit: it is built for children from about age 3, adult beginners and families. That matters, because most kids' language apps drop children right when language learning gets interesting. A 9-year-old is ready for sentence construction, conversation practice, and real grammar patterns. Most "kids apps" have nothing left to offer them.

The app maps to the CEFR framework (the European standard for language proficiency), covering Pre-A1 through B1 across seven planets. Each planet is a proficiency stage, so you can actually answer "Where is my child, and where are they going?"

Best fit: Children from about age 3 (and adult beginners) who are actively learning English as a second language and need structured, progressive skill building.

Game variety and engagement: why 17 game types beat 3 or 4

This is where the three apps differ most.

The boredom problem

Picture a 6-year-old who starts on Duolingo in September. She loves it at first. The owl is cute. The sounds are fun. She does her lessons every day for a week and a half.

Then one afternoon she tells you it's the same game again.

She'd have a point. Duolingo's core experience cycles through a small set of mechanics: tap the correct translation, put words in order, type what you hear. The content changes, but what the child actually does stays much the same. An adult with their own reasons to learn can live with that. A 6-year-old usually can't.

How Lingokids handles variety

Lingokids does better here. It offers songs, interactive stories, coloring games, cooking games, and puzzle activities. The variety holds younger children's attention, and the production quality is high. A child can bounce between a music video and a matching game and a drawing activity without feeling like they are repeating the same thing.

The trade-off is that a lot of these activities put entertainment first. A cooking game teaches some vocabulary, but it won't go back over the words your child struggled with yesterday. Kids stay busy, but the English doesn't go very deep.

How Small Universe solves retention

Small Universe goes the other way. With seventeen different game types, a child can practice the same vocabulary through matching, bubble popping, memory flips, word building, sentence scrambling, rhyming, conversation simulations, and more. They don't feel like they're "doing the same thing."

Here's the full list:

The GameWheel is the design choice that matters most here. From age 6, a spinning wheel picks at random which game type your child will play before each lesson. (Children aged 3-5 don't see the wheel. The app picks a game for them and still varies it from lesson to lesson.) It only offers games suited to your child's age, so a 3- or 4-year-old gets 11 game types, a 6-year-old gets 16, and a 7-year-old gets all 17. Every lesson starts with a surprise, even when the vocabulary stays the same.

The wheel exists because of the 2% retention problem. An unpredictable format keeps a child paying attention, and attention is what makes words stick. If you want the neuroscience behind this, we wrote a longer piece on why most English apps bore kids within a week or two.

The research behind variety

We didn't invent this idea. Cognitive science calls it "interleaving," which means mixing different kinds of activity during learning instead of doing one kind at a time. Studies of interleaved practice (Rohrer & Taylor, 2007) found that mixing problem types improves long-term retention compared with blocked practice, even though it feels harder while you're doing it.

That is what the seventeen game types are for. They build interleaving into the practice itself.

Curriculum and CEFR coverage

What is CEFR and why should parents care?

The Common European Framework of Reference for Languages (CEFR) is the international standard for measuring language ability. It runs from A1 (absolute beginner) to C2 (native-like mastery). Schools and employers around the world use it to assess language skills.

For parents, CEFR answers a simple question: "Is my child actually progressing, or are they just playing?"

Duolingo's curriculum

The main Duolingo app maps its courses to CEFR, up to B2 in its biggest courses. But it's built for teens and adults, with no path designed for young children. Duolingo ABC has no CEFR mapping at all because it teaches reading, not language proficiency.

Lingokids' curriculum

Lingokids references 650+ "learning goals" across all subjects. It says its English Lessons follow the CEFR, but publishes no level-by-level map. Its English content draws on Oxford University Press materials, which is a credible source. But English is only one of several subjects in the app, so less of each session goes to language. A child might spend 15 minutes in Lingokids and meet English vocabulary for only 5 of them.

Small Universe's curriculum

Small Universe maps its entire structure to CEFR:

Each lesson usually introduces 8-12 new words, and lessons mix new words with review of ones your child has already met. That follows a well-supported point from Paul Nation's vocabulary research: a learner needs to meet a word many times before it sticks. Across all seven planets, the app teaches about 950 words.

The app currently has 102 lessons across seven planets, all of them free.

If you want to see exactly where your child stands on a globally recognized language scale, Small Universe is the only one of these three that maps each stage of a children's course to a CEFR level.

Try it now: Small Universe lets your child start a lesson straight away as a guest, with no account. See the CEFR progression for yourself at smalluni.com.

Pricing breakdown

Money matters. Here's what each app costs in the US at the time of writing (prices vary by country and platform).

Duolingo ABC is the clear pricing winner: it's completely free with no ads. If it fits your child's needs (native English speaker learning to read), it's hard to argue with free.

Lingokids costs more. Lingokids Plus is about $15/month, or roughly $72-$90/year in the US depending on where you subscribe, and for that you get a polished app with no ads. The free plan, with its small daily allowance (about 10 activities a day at the time of writing), is enough to find out whether it works for your child.

Small Universe is free: all 102 lessons, no subscription, no ads and no credit card. A child can play as a guest, and a parent can sign in with an email code to back up progress. If optional paid add-ons (speaking practice, teacher tools) arrive later, they won't block today's lessons.

Safety, ads, and privacy

When your 4-year-old uses an app on their own, safety comes before any feature. If screen time worries you, our article on screen time and language learning research covers what the studies actually say.

Duolingo (main app)

Free adult accounts show ads between lessons; under-13 (US) accounts don't. The Super subscription removes them. The social features (leaderboards, friend lists) are aimed at older learners; under-13 accounts are private and can't be followed.

Duolingo ABC

No ads, no in-app purchases, no social features. Duolingo clearly learned from the main app's problems and built ABC as a safe, closed space.

Lingokids

kidSAFE certified, completely ad-free, no in-app purchases beyond the subscription itself. The parent dashboard shows you clearly what your child is doing.

Small Universe

No account is needed to start the game, and a child's progress stays on the device unless a parent signs in to back it up. No ads, no social features, no way for a child to interact with strangers. The Parent Zone shows how the app is being used, behind a simple gate that keeps little fingers out.

All three apps (excluding the main Duolingo app) score well on safety. The kids' app space has gotten much better at this.

Verdict by age group

No app suits every child. Here's what we'd honestly recommend at each age.

Ages 3-4: first steps

Best choice: Lingokids or Small Universe

At this age, holding their interest comes first. Your child needs bright colors, simple interactions, and immediate feedback. Lingokids is very good here, with songs and activities full of sound and color. Small Universe opens 11 of its game types to 3- and 4-year-olds, including simple ones like Matching, Bubble Pop, Memory Flip and Listening Lab, and the youngest players never lose a heart.

Duolingo ABC works if your child is a native English speaker ready for letter recognition. If English is a new language for your child, skip it for now.

Our pick for ESL learners: Small Universe. It adapts to age rather than to scores: players aged 3 to 5 get no Game Wheel, spoken instructions and no hearts to lose, and words a child misses in Matching come back for another try, without a parent having to step in. For a fuller breakdown, see our list of the best English apps for 3-4 year olds.

Ages 5-7: the window that matters

Best choice: Small Universe

This is the age where structured progression matters most. Your child is cognitively ready for real language learning, not just exposure. They can handle harder game types and follow a storyline, and they're starting to build sentences.

Picture a pair of 6-year-old twins. They've outgrown the Lingokids songs, and Duolingo feels too text-heavy and grown-up. Games like Boss Battle and Word Hunt are more likely to hold them, because those feel like doing something cool rather than something educational.

This is the age where Small Universe's advantages show. Twelve of the 17 game types are open at five, 16 at six and all 17 at seven, the space story gives kids a real reason to keep going, and the CEFR mapping lets you track actual progress in English. We also have a dedicated guide to the best English apps for 5-7 year olds.

See it in action: From age 6, the GameWheel spins and picks a random game for each lesson, so your child never knows what's coming next. Try Small Universe free.

Ages 8-10: the gap few apps fill

Best choice: Small Universe (one of the few options designed for kids aged 8-10)

Here's where the comparison falls apart. Lingokids stops at age 8. Duolingo ABC stops at age 6. The main Duolingo app is built for a general audience of teens and adults.

For children aged 8-10 who are learning English, there's a real gap. They're too old for toddler apps and too young for adult apps. Small Universe fills it with Sentence Scramble, Chain Reaction, and Conversation Sim, games pitched at the level of older children.

A 9-year-old on Jupiter is working with several hundred words, constructing sentences, and practicing real conversation patterns. That's actual language learning, not busy work.

Say your 9-year-old is preparing for an A2-level school assessment. At that age most apps feel either too babyish or too adult. A space theme can keep her interested without being embarrassing to play in front of school friends.

The bottom line

There's no single "best" app, only the best one for your child right now, at their age and with their needs.

Choose Duolingo ABC if your child speaks English at home and needs help learning to read. It's free and well made, and it sticks to one job.

Choose Lingokids if your child is under 5 and you want early learning across several subjects, with English as one of them.

Choose Small Universe if your child (age 3 or older) is learning English as a second language and you want a structured CEFR-mapped curriculum that builds step by step, with enough game variety to keep them coming back past Day 30.

Building a consistent daily routine matters more than which app you pick. Read the 2% retention figure as a warning. An app your child abandons after two weeks taught them nothing, however good its curriculum looked on paper. That is why game variety matters so much: it decides whether the app sits unopened in a folder or actually builds a language. For more options, see our roundup of the best English games for kids.

Start free, no account needed. Small Universe runs in your browser, with no download and no credit card, and all 102 lessons are free with no subscription. Your child gets a friendly alien and 17 ways to learn English. Try it at smalluni.com.

Last updated: October 2026. App features and pricing may change. We're the team behind Small Universe, so yes, we're biased, but we've done our best to be fair. Try all three and let your child decide.

Frequently asked questions

Is Duolingo good for young kids learning English?

The main Duolingo app is built for teens and adults. Children under 13 can use it through a parent-email account, but the pace is pitched at older learners. Duolingo ABC, for ages 3-6, is free with no ads, but it teaches native English speakers to read rather than teaching English as a new language.

How much do these apps cost?

At the time of writing in the US, Lingokids has a free plan with about 10 activities a day, or Lingokids Plus at about $15 a month. Duolingo ABC is free, and Super Duolingo costs about $12.99 a month. Small Universe, our own app, is free: all 102 lessons, no subscription, no ads and no credit card.

Which app works for an 8 to 10 year old?

Lingokids stops at age 8 and Duolingo ABC at age 6, while the main Duolingo app is built for teens and adults. Small Universe, which is our own app, keeps going with Sentence Scramble, Chain Reaction and Conversation Sim, and its Saturn planet reaches from A2 into B1.

Do these apps follow the CEFR?

The main Duolingo app maps its courses to CEFR, up to B2 in its biggest courses, but has no path designed for young children, and Duolingo ABC has no CEFR mapping. Lingokids says its English Lessons follow the CEFR but publishes no level-by-level map. Small Universe maps each planet to a level, from Pre-A1 to B1.

Sources

This guide draws on the following research and reference works. It is written by Paul B.

• Business of Apps (2026). App Retention Rates & Education App Benchmarks (Day 1 and Day 30 retention figures).
• Rohrer, D., & Taylor, K. (2007). The shuffling of mathematics problems improves learning. Instructional Science, 35, 481-498.
• Nation, I. S. P. (2001). Learning Vocabulary in Another Language. Cambridge University Press.
• Krashen, S. D. (1982). Principles and Practice in Second Language Acquisition. Pergamon Press.