Study guide
3.4 Errors, Slips, and Interlanguage
Cambridge TKT Teaching Knowledge Test
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1 Introduction & Exam Overview
0.1 About the Cambridge TKT: Modules, Format, and Band Scores 0.2 TKT Task Types, Exam-Day Strategy, and How to Use This Guide
2 Chapter 1: Describing Language - Grammar, Lexis, Phonology, and Functions
1.1 Grammar Concepts and Sentence Structure 1.2 Lexis, Word Formation, and Semantic Relations 1.3 Phonology, Sound Systems, and Connected Speech 1.4 Language Functions and Exponents
3 Chapter 2: Language Skills and Sub-Skills
2.1 Receptive Skills - Reading and Listening Sub-skills 2.2 Productive Skills - Speaking and Writing Sub-skills 2.3 Integrating Skills and Text Analysis
4 Chapter 3: Background to Language Learning
3.1 SLA Theories and L1 vs. L2 Acquisition 3.2 Learner Characteristics, Learning Styles, and Autonomy 3.3 Learner Needs and Motivation 3.4 Errors, Slips, and Interlanguage
5 Chapter 4: Background to Language Teaching & Assessment
4.1 Presentation Techniques and Introductory Activities 4.2 Practice Activities and Task Types 4.3 ELT Methodologies, Approaches, and Frameworks 4.4 Assessment Types, Purposes, and Task Formats 4.5 Assessment Methods: Self, Peer, Portfolio, and Continuous Assessment
6 Chapter 5: Lesson Planning & Aims
5.1 Identifying and Selecting Lesson Aims 5.2 Components of a Lesson Plan and Stage Sequencing 5.3 Anticipating Learner Problems and Planning Solutions 5.4 Planning a Sequence of Lessons: Assumptions, Timetable Fit, and Common Sequences 5.5 Choosing Assessment Activities for a Lesson or Sequence
7 Chapter 6: Selection and Use of Teaching Resources
6.1 Coursebook Evaluation, Adaptation, and Supplementation 6.2 Supplementary Materials, Authentic Texts, and Teaching Aids 6.3 Reference Resources and Educational Technology
8 Chapter 7: Classroom Language & Interactions
7.1 Teacher Classroom Language, Instructions, and Eliciting 7.2 Functions of Teacher Language and Classroom Exponents 7.3 Learner Classroom Language and Interaction 7.4 Appropriacy of Teacher Language: Simplicity, Formality, and Using L1
9 Chapter 8: Classroom Management & Dynamics
8.1 Teacher Roles in the Communicative Classroom 8.2 Grouping Learners, Seating, and Interaction Patterns 8.3 Managing Classroom Participation and Pace 8.4 Classroom Rules, Routines, Praise, and Managing the Teaching Space
10 Chapter 9: Correcting Learners and Giving Feedback
9.1 Categorising Learners' Mistakes by Linguistic Type 9.2 Errors, Slips, and Deciding When to Correct 9.3 Immediate and Delayed Correction Techniques 9.4 Giving Effective Feedback and Encouraging Self-Correction
3.4 Errors, Slips, and Interlanguage
Key Takeaways Explain This Topic AI
Mistakes (slips) are temporary performance lapses in structures the learner knows and can self-correct, whereas errors reflect gaps in the learner's underlying interlanguage knowledge.
Interlanguage is a dynamic, rule-governed, evolving linguistic system constructed by L2 learners as they move from their native language (L1) toward target language (L2) norms.
Developmental errors arise naturally from universal learning processes such as overgeneralisation (e.g., applying regular -ed past tense rules to irregular verbs like goed).
Interlanguage errors also stem from L1 transfer (mother-tongue interference), where structural, phonetic, or pragmatic rules of the native language are applied to the L2.
Fossilisation occurs when non-target interlanguage forms become permanently fixed in a learner's speech/writing, often due to communicative effectiveness, lack of corrective feedback, or age.
Last updated: July 2026
3.4 Errors, Slips, and Interlanguage
Errors are an inevitable, natural, and positive indicator of language learning. Rather than viewing non-target production as evidence of failure, modern ELT views student errors as vital evidence of active cognitive processing and hypothesis testing. For the Cambridge TKT, teachers must accurately distinguish between different categories of non-target language, analyze their cognitive origins, and apply appropriate corrective feedback strategies.
Categorising Learner Output: Slips, Errors, and Attempts
Linguist Pit Corder and ELT author Julian Edge established an essential taxonomy for classifying non-target language forms produced by L2 learners:
1. Slips (or Mistakes)
Definition : A temporary breakdown in performance. The learner already possesses the underlying grammatical or lexical knowledge but fails to produce it correctly due to distraction, fatigue, anxiety, or high cognitive load.
Key Characteristic : The learner is fully capable of self-correction when their attention is drawn to the item (e.g., a student writing He go to school who immediately changes it to He goes when the teacher points to the sentence).
2. Errors
Definition : A systematic deviation reflecting an incomplete underlying competence. The learner's internal interlanguage grammar currently generates the incorrect form because the target rule has not yet been acquired or internalised.
Key Characteristic : The learner cannot self-correct because they do not know the correct rule or form yet. Explicit teaching, clarification, or input restructuring is required.
3. Attempts
Definition : An utterance where a learner tries to express an idea or meaning for which they have not yet learned the necessary target structures or vocabulary.
Key Characteristic : The output may appear fragmented or highly non-standard, as the learner uses circumlocution, gestures, or native language words to get their message across.
Output Category Underlying Competence Self-Correction Possible? Recommended Teacher Action
Slip / Mistake Possessed (temporary lapse) Yes, immediately Prompt self-correction (gestures, echoing, finger correction)
- Error Incomplete / Developing No (requires scaffolding) Clarify rule, provide recasts, re-teach structure
- Attempt Absent (trying new meaning) No Provide target vocabulary/phrase (reformulation)
- Interlanguage Theory
Coined by Larry Selinker in 1972, Interlanguage (IL) refers to the interim, independent linguistic system created by a second language learner as they progress from their mother tongue (L1) toward the target language (L2).
Interlanguage is not merely an unorganised collection of errors; it is a systematic, rule-governed, dynamic, and permeable language system in its own right. As learners receive more comprehensible input and test new hypotheses, their interlanguage constantly restructures itself, moving closer to target language norms. [ Native Language (L1) ] ==> ( Interlanguage Continuum: IL1 -> IL2 -> IL3 ) ==> [ Target Language (L2) ]
Causes and Origins of Errors
Errors generated by a learner's interlanguage system stem primarily from two main cognitive sources:
1. Developmental Errors (Overgeneralisation)
Developmental errors are universal errors made by L2 learners across different native language backgrounds (and often by L1 children). They occur through overgeneralisation —when a learner discovers a regular rule in the target language and extends it to irregular exceptions where it does not apply.
Past Tense Overgeneralisation : Adding regular -ed to irregular verbs (e.g., she goed , he runned , they buyed ).
Plural Overgeneralisation : Adding regular -s to irregular nouns (e.g., two childs , three mouses , four teeths ).
Modal Auxiliary Overgeneralisation : Adding third-person -s to modal verbs (e.g., he musts go ).
Key Concept : Overgeneralisation is positive proof that the learner is actively identifying structural patterns and testing hypotheses, rather than simply parroting memorized phrases.
2. L1 Transfer (Mother-Tongue Interference)
Errors also occur when learners transfer structural, phonological, or lexical rules from their native language into the L2.
Negative Transfer (Interference) : Occurs when L1 and L2 structures differ, resulting in incorrect production. For example:
A Spanish speaker saying "I have 20 years" (translating Tengo 20 años ) instead of "I am 20 years old" .
A French speaker saying "I like very much this movie" (placing the adverb between verb and object) instead of "I like this movie very much" .
A German speaker transferring verb-second (V2) word order into an English main clause after a fronted adverbial: "Yesterday went I to the cinema" instead of "Yesterday I went to the cinema" .
Positive Transfer : Occurs when L1 and L2 structures align (e.g., similar vocabulary cognates or parallel word order), facilitating accurate L2 production.
The Phenomenon of Fossilisation
Fossilisation occurs when non-target interlanguage forms become permanently fixed in a learner's language production, resisting change despite exposure to correct input, formal instruction, and explicit feedback.
Causes of Fossilisation:
Communicative Effectiveness : The non-target form successfully conveys meaning, so there is no communicative pressure to correct it (e.g., saying "Yesterday I go to market" is clearly understood).
Lack of Feedback : The learner rarely receives corrective feedback or exposure to accurate forms.
Age & Affective Factors : Reduced neural plasticity or emotional satisfaction with current conversational ability.
To combat fossilisation, teachers use consciousness-raising tasks and noticing activities (Schmidt's Noticing Hypothesis), drawing learners' explicit attention to the gap between their interlanguage output and target forms.
Error Treatment in the Classroom
Deciding how and when to correct errors depends on the lesson focus:
Fluency Focus (e.g., free discussion, communicative role-play): Avoid immediate interruptions. Record errors silently and deliver delayed feedback on the board after the activity.
Accuracy Focus (e.g., controlled grammar practice): Correct key target errors promptly using gentle techniques such as recasting ("Student: He go to town. Teacher: Ah, he goes to town?"), finger correction , or prompting self-correction.