What Is Comprehensible Input? Reach Language Fluency Faster with the CI Approach

Key takeaways:

• Comprehensible input is a fast and effective way to acquire a new language. It focuses on consuming (listening to or reading) material you mostly understand, rather than memorizing grammar or vocabulary.
• i+1 is the key. Progress is fastest when the input you are exposed to is slightly above your current level, but you can still understand most of it. This is called the i+1 zone.
• Active engagement is essential. Just listening or reading isn’t enough; you need to summarize, retell, or reflect on the material you’ve consumed.
• Consistency matters. Daily exposure is critical for progress and fluency.

What is a comprehensible input

Comprehensible input is a key part of a group of language-learning hypotheses developed by the linguist Stephen Krashen in the 1970s and 1980s. 

Krashen created the “input hypotheses” as a model for learning a second (or third) language. The model consists of five hypotheses that he believes are the foundation for learning a new language. 

Here’s a simplified breakdown of each of the five hypotheses:

1. Input hypothesis: The core of Krashen's language learning method is comprehensible input (CI). CI is the idea that learners make the most progress when the language they’re exposed to is largely understandable but includes elements just beyond their current ability. Krashen described this as the i+1 level. Where i represents the learner’s current language level, and +1 signifies the next step in their language development.

2. Acquisition-learning hypothesis: According to this hypothesis, language should be acquired, not learned. In other words, focusing on grammar rules and memorizing long vocabulary lists counts as learning, not acquisition. And it’s not an effective way to quickly master a second language. 

3. Monitor hypothesis: This suggests that consciously learning a language (studying grammar rules and memorizing vocabulary) can help you to monitor your language level, but it doesn’t directly lead to real improvement in your language skills.

4. Natural order hypothesis: This is the idea that all learners will acquire a language in the same order, regardless of what is taught first in the classroom. 

5. Affective filter hypothesis: The final hypothesis of Krashen's model is that a learner's mood heavily influences how easily they acquire the language. Having negative emotions around learning a language, like fear or embarrassment, will significantly limit one's ability to progress.

In essence, comprehensible input is the idea that in order to learn a language effectively, you need to be able to generally understand what you’re hearing or reading, but there should also be elements of it that are just out of reach of your current level.

How the comprehensible input hypothesis help in language learning

Now that you know what the comprehensible input language learning model is, let’s take a look at the best way to use it in the real world. 

In order to effectively use Krashen’s comprehensible input hypothesis, you first need to understand his approach to learning. Krashen's learning model focuses on understanding written or auditory input rather than studying rules or memorizing lists. The goal is to expose yourself as much as possible, through reading and listening, to the language in a way that feels mostly understandable, but still challenges you.  

Here are some effective ways to do that:

• Figure out the +1 level. This is the level of language where you can understand the majority of what you’re hearing or reading, but it still pushes you. 
• Choose your content wisely. Choose podcasts, videos, or shows that interest you, you enjoy, and know the topic. Subtitles and transcripts can help to bridge any gaps.
• Engage in meaningful conversation. Speaking with a native or fluent speaker exposes you to authentic language, but the speaker must use words and phrases at a speed that you’re comfortable with. 
• Focus on understanding, not perfection. Don’t try to translate every word. The key is to understand the general context first, and the details will become clearer over time.
• Use visual cues where possible. Our brains absorb more information when it’s accompanied by visual cues like videos or graphs.

Top comprehensible input examples you can start today

You can apply the comprehensible input approach at any stage of language learning; the key is finding material that’s mostly understandable but still pushes you a little beyond your comfort zone. 

Before you start, make sure you know how to gauge whether the materials you’re using are the right level for you. 

Here’s how to quickly check the comprehension level: 

• You can understand 70% to 90% of the material you’re listening to or reading.
• You don’t have to constantly push pause or use a translation tool. 
• You can follow the gist of the main ideas or storylines.
• A good rule of thumb is that if you’re feeling lost every couple of sentences, the material is too advanced for you, and if it feels effortless, it’s time to move up a level. 

Beginner (A1–A2): slow YouTube channels, graded readers, picture stories

If you’re at the beginning of your language learning journey, then at this stage you need slow, clear, and visually heavy materials that use simple vocabulary and lots of context clues.

Here are some resources to try:

• Graded readers: Look for graded reading books like the English Oxford Bookworms range, as these are written for specific levels and should include lots of visual prompts.
• Language apps: A language app like Promova will assess your current proficiency and provide resources personalized to your level.
• YouTube channels: Use YouTube channels that are aimed at beginners, like the English Learning Hub.
• Children’s resources: Reading books or watching programmes aimed at younger native children are also good for adult learners, as they use simple vocabulary and lots of visual cues.

Intermediate (B1–B2): podcasts with transcripts, easy news, series with subtitles

You’ve reached the intermediate level once you can understand everyday topics and manage basic conversation with ease.

Many learners find themselves stuck here, in a phenomenon known as the intermediate plateau. Focusing on comprehensible input and engaging with topics that genuinely interest you can help you move past this hump. Here are some resources to use at the intermediate level:

• Podcasts with transcripts: The BBC learning English podcast and Coffee Break French are great intermediate-level resources that can be used with or without subtitles.
• Favourite books: If you have a childhood favourite, like Harry Potter, that you know well, try reading it in your target language. Since you’re familiar with the story, it's an ideal source of comprehensible input that’s both enjoyable and effective.  
• Simplified news stories: Reading simplified news stories or reading a news story in your first language and then a news story on the same topic in your target language is a great source of comprehensible input. 
• TV series with subtitles: Choose shows you already know (like Friends or The Office) and consider using the subtitles if necessary. 

Advanced (C1): native podcasts, audiobooks, interviews, lectures

Once you reach the advanced level, you will be able to consume authentic, native content. Not only will this expand your understanding, but native content will be able to help you refine nuance, tone, and cultural understanding. 

Examples of native resources:

• Podcasts: TED Talks, native news channels, or any other podcast on topics you’re interested in. 
• Audiobooks: Depending on your level, you can explore new fiction or nonfiction audiobooks or listen to the audiobook version of a book you’ve already read in your native language. This way, you’ll understand the context but should still be challenged by new vocabulary and expressions.
• Native conversation: One of the most effective ways to improve at this stage is through frequent conversations with native speakers. Regular interaction strengthens both your speaking and listening skills. If you don’t have access to native speakers or can’t travel to a country where the language is spoken, try working with an online tutor for English speaking practice or using an AI-powered conversation tool instead.

CI routine: step-by-step plan for daily language progress

To make consistent progress with the comprehensible input (CI) method, you need to build it into your daily routine. Here’s a step-by-step plan to help you structure your daily routine.

1. Goal setting: 

• Start every day by setting a clear list of language learning goals. 
• Decide how much time you’ll dedicate that day (aim for at least 20 minutes). 
• Choose your content source (language app, tutor, podcast, YouTube, or a chapter of a book) or choose a topic to focus on (e.g, weather, greetings, health).

2. Follow the CI loop: 

• Preview: Skim the content to get an overall idea of the topic and to check it meets the i+1 CI level.
• Active listening/reading: Engage with your chosen material for the full time you’ve set aside, ideally in a distraction-free setting. Listening while walking the dog or doing light chores can be a great way to be productive, but multitasking with anything too demanding will reduce how much you absorb. 
• Quick check: Using subtitles, podcast notes, or a language app to check any areas you found particularly difficult.
• Light retell: Summarize what you just consumed, out loud or in writing, to reinforce comprehension and recall.
• Log: Note new words or phrases in a language journal.

3. Track your progress:

• Note what topic you covered, how difficult you found it, and any new words you acquired.
• Use focus techniques like the Pomodoro method — study in short bursts (for example, 25 minutes of learning followed by a 5-minute break) to stay motivated and avoid burnout. 

4. Weekly or monthly progression:

• Gradually increase the difficulty of your content.
• Swap media types so you get a good balance of audio and visual input.
• Add narrow sessions that focus on a specific topic but in greater detail to deepen comprehension.
• Consider using an online language learning platform like Promova to track and measure your progress.

Comprehensible input vs traditional study

Many different language learning methods exist, and each method has its own unique set of strengths and weaknesses. Here’s how the comprehensible input hypothesis approach compares to more traditional methods. 

Common mistakes in using CI (and how to fix them)

Using comprehensible input hypotheses to learn a language is a powerful way to learn naturally, but that doesn’t mean there aren’t pitfalls. Here are some common mistakes learners make and how to correct them.

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1. Choosing the wrong input

Probably the most common mistake made with CI is choosing input (audio or written) that is too difficult. The sweet spot for learning with CI is engaging with material that you generally understand (aim for understanding 70-90% of it), but still challenges you.

Fix: Use our quick comprehension check guide above before starting any new material to make sure it's at the i+1 level.

2. Consuming passively

Simply listening or reading something without focusing and checking your understanding will not lead to meaningful progress.

Fix: Use a learning loop to actively engage. Summarizing what you’ve learnt, checking understanding, and monitoring your progress help you to stay on track. 

3. Sticking to the same difficulty level

Sticking with the same level of difficulty for weeks on end might feel comfortable, but without any challenge, you won’t progress.

Fix: Regularly review your progress and gradually use inputs with a higher level of difficulty.  

4. Not spending enough time

The comprehensible input approach to language learning is both effective and efficient. But to improve your language skills quickly, you need active engagement and consistent exposure. Learners need to interact with a large amount of input regularly, not just passively consume it.

Fix: An hour once a week, unfortunately, won’t cut it. Build the CI method into your daily schedule in a way that is enjoyable and fits in with your life.

How Promova helps with CI learning

Promova is a one-stop language learning platform that can help you effectively and efficiently build real-life language skills. Gone are the days of endless grammar exercises and memorizing long vocabulary lists. In its place are CI-inspired learning exercises, AI-driven conversational practice, and online classes to help you build confidence and skills.

The most important aspect of learning any language is being able to hold a conversation in different scenarios. And Promova can help you get there. Here are some of the ways Promova will help you to build fluency:

• AI-powered conversation practice. Practice real conversations at the right level for you with AI Tutor.
• Topic-based lessons. CI learning relies on you enjoying and actively engaging with lessons. That’s much easier to do when you focus on topics you’re genuinely interested in and learn a language you know you will use. 
• Personalized learning. Promova is designed to adapt to your current level and goals. The English learning app follows the comprehensible input hypothesis by growing with you.
• Certified English tutors and small group classes. Building fluency means regularly engaging in conversation. This can be difficult if you don’t know many native speakers. Promova offers small-group classes or 1:1 sessions with certified English tutors to help you with real-world speaking practice, build confidence, and level up your language skills.

Final thoughts

The comprehensible input language learning model offers one of the most natural and effective ways to acquire a second language. Developed in the 1970s by linguist Stephen Krashen, the hypothesis emphasizes acquisition, absorbing language through carefully selected input, rather than the more traditional approach of rote learning and repetitive drills. 

In simple terms, it suggests the fastest way to learn a new language is by listening to and reading materials you mostly understand, but that includes elements just beyond your current level, the i+1 zone.

Podcasts, YouTube videos, books, TV shows, and news articles all make excellent sources of comprehensible input. The key is consistency, choosing the right level, staying actively engaged, and regularly monitoring your progress.