Tracking Comprehensible Input: A Practical Guide

Stephen Krashen's "comprehensible input" hypothesis is one of the most-cited ideas in language acquisition: you learn a language by understanding messages slightly above your current level (the famous "i+1"). The challenge is that "slightly above" is subjective — and tracking it is harder than tracking generic minutes.

Here's a practical approach.

What counts as comprehensible input

Input is comprehensible when you understand 70–95% of it without translation. Below 70%, you're decoding, not acquiring. Above 95%, it's review, not new acquisition.

This is the famous "i+1" zone — just above your current level. Most things you naturally consume in your target language are either too hard (i+5) or too easy (i+0). Both have value but they're not comprehensible input in Krashen's sense.

Examples by level

• A2: graded readers (e.g., Olly Richards' Short Stories), super-slow podcasts (News in Slow X), early-elementary children's TV.
• B1: dubbed kids' shows, podcasts for learners (e.g., Spanish Pod 101), simplified news.
• B2: native podcasts at slow pace, YA novels, dubbed TV with target-language subtitles.
• C1: standard native content; the constraint shifts to topic familiarity, not language complexity.

How to track it

Add a tag specifically for "CI" (comprehensible input) sessions. Keep it separate from generic "listening" or "reading" tags. CI requires more focus than passive listening, so a 30-minute CI session is genuinely worth more than a 30-minute background-podcast session.

Some learners track "active" vs "passive" minutes:

• Active: focused, no multitasking, actively comprehending
• Passive: background, multitasking, bonus exposure

Don't lie to yourself. If you're cooking dinner, that's passive. Both count, but they don't compound at the same rate. Time vs output tracking covers the broader principle.

The 70–95% test

How do you know if content is comprehensible without testing every word? Quick checks:

• Stop the audio every 60 seconds. Can you summarise what was said? If yes — comprehensible. If you draw blanks — too hard.
• For reading: cover up the dictionary. Read a paragraph. Can you keep going? If you stopped 5+ times to look up words, it's too hard.
• If you laugh, react, or feel emotion at the right moments, you're getting enough.

Common mistakes

1. Content that's too hard. Watching native speakers chat at full speed when you're A2 is white noise. It feels productive but isn't.
2. Content that's too easy. Re-reading the same beginner book ten times. Comfortable but not productive.
3. Treating English subtitles as input. They're a crutch — useful occasionally, but the comprehensible input is happening for English, not your target.
4. Not tracking it. CI without tracking blends into passive listening in your dashboard. The categories matter.

How much CI per week

Krashen's research suggests at least 50% of your study time should be CI for optimal acquisition. Most learners are below 30%. Tracking is the only way to know which side you're on.

For Krashen's hypothesis in detail, see the input-hypothesis explainer.