What happens after a learner makes an error, and how does the instructor's response shape the next turn? Investigating these exchanges across classrooms requires context-sensitive annotation that is difficult to scale manually. We introduce SLA-LENS, an end-to-end LLM-assisted framework that connects classroom transcripts to structured pedagogical annotations and evidence-linked descriptive analytics. Grounded in interactionist Second Language Acquisition (SLA) theory, its annotation schema captures second language learner errors, pedagogical functions, and uptake or repair while accounting for speaker roles, conversational context, and hierarchical labels. We apply the framework to 40 authentic online L2 Spanish classroom transcripts comprising over 21,000 sentence-level instances. We evaluate proprietary and open-weight LLMs, including task-specific QLoRA adaptation, using expert-reviewed gold annotations, held-out silver data, and metrics sensitive to different types of annotation error. A deterministic reporting layer generates reproducible visualizations of participation, feedback, learner errors, uptake, and temporal interaction patterns, linked to supporting transcript evidence. By making these patterns accessible and inspectable, SLA-LENS supports systematic classroom discourse research, pedagogical reflection, and curriculum design.
Figures & tables
Figure 1: Overview of the SLA-LENS end-to-end framework. Classroom transcripts are structured and annotated using contextual LLMs guided by a theory-informed CSLA schema. Annotation quality is assessed through diagnostic-sensitive evaluation, while a deterministic analytics layer computes descriptive interactional measures and candidate event associations. SLA-LENS produces an annotated transcript and an evidence-linked analytical report with participant-level statistics, temporal visualizations, and supporting transcript examples.
Corpus statistic
Count
Transcripts
40
Sentence rows
21,835
Approximate words
106,336
Instructor rows
14,648
Learner rows
7,187
Single-label rows
21,106
Table 1: Overview of the SLA-LENS annotated corpus. Counts are derived from GPT-generated annotations rather than independently validated gold labels.
Family
Labels
Role
Function and example
Prompt
P:I, P:IQ, P:CQ
Instructor
Elicits learner production through instructions, information-seeking questions, or clarification questions. Example: “So, the first question for today is: ¿cuál es el tema de la Unidad 7?” [Eng: “What is the topic of Unit 7?”]
Prompt response
PR
Learner
Responds to the preceding prompt. Example: “El tema de la Unidad 7 es la justicia.” [Eng:“The topic of Unit 7 is justice.”]
Responds to learner production through correction, reformulation, elicitation, metalinguistic info, evaluation, or acknowledgment. Example following a lexical error: “Justicia means justice.”
Other instructor functions
A, RN, CM, CoM
Instructor
Answers learner questions, reacts to content, manages classroom logistics, or regulates conversational flow. Example after a learner describes a large family: “That is a big family!”
Uptake / repair outcome
R:S, R:IR, R:Ack, R:NR
Learner
Characterizes a learner response following feedback as successful repair, incomplete repair, acknowledgment, or no uptake. Example following correction: “Mi hermana tiene trece años.”[Eng: “My sister is thirteen years old.”]
Student prompt
SP, SP:I, SP:IQ, SP:CQ
Learner
Initiates or extends interaction through questions, instructions, or requests for clarification. Example: “¿Cómo se dice kite en español?”[Eng:“How do you say kite in Spanish?”]
Table 2: Condensed CSLA annotation schema used by SLA-LENS. Classroom-event and learner-error annotations are stored independently. Full definitions, decision rules, and examples are provided in Appendix A .
Analysis dimension
Descriptive measures
Participation
Instructor and learner contributions; individual learner production.
Learner errors
Frequency, type distribution, and learner-normalized error incidence.
Pedagogical events
Prompt and feedback subtype distributions; uptake/repair outcomes.
Temporal patterns
Distribution of annotated events across lesson intervals.
Error → Feedback
Candidate associations between error-marked learner production and subsequent feedback.
Feedback → Uptake
Candidate associations between instructor feedback and subsequent learner uptake/repair.
Table 3: Descriptive interactional measures supported by SLA-LENS. Sequence-based measures represent proximity-derived candidate associations rather than verified pedagogical episodes.
Prediction relation
Credit
Exact label
1.00
Correct family, wrong subtype
0.70
Correct role, wrong family
0.25
Role-incompatible prediction
0.00
Correct labels, incorrect order
×0.85
Table 4: Base credits for hierarchical annotation similarity. Multi-label scoring additionally accounts for partial matches and unsupported labels.
Model
Hard Acc.
Soft Score
Feedback F1
Uptake F1
Error F1
Error Hard Acc.
GPT-4.1
76.72
84.12
87.57
76.64
81.40
96.63
Gemma 4 12B
54.30
67.20
65.10
45.80
61.70
90.80
Llama-3.1-8B
58.70
70.90
69.80
50.60
65.40
91.90
Qwen3-8B
62.40
73.80
73.50
55.20
69.10
92.80
Qwen3-8B (QLoRA)
69.80
79.60
81.20
65.40
75.80
94.90
Table 5: Annotation performance against the expert-reviewed gold transcript. All values are percentages except Soft Score, which is on a 0-100 scale.
Model
Hard Acc.
Soft Score
Feedback F1
Uptake F1
Error F1
Error Hard Acc.
Gemma 4 12B
66.80
76.40
76.20
58.70
70.30
94.20
Llama-3.1-8B
70.20
79.10
79.80
63.40
74.10
95.30
Qwen3-8B
74.10
82.20
83.60
67.90
77.80
96.10
Qwen3-8B (QLoRA)
81.30
87.10
89.20
76.50
84.10
97.20
Table 6: Agreement with GPT-generated annotations on five held-out silver transcripts. Silver agreement measures reproduction of GPT annotations rather than agreement with expert judgments.
Appendix figures & tables10 assets
Supplementary material from the paper’s appendix.
Appendix
Label
Definition
P:I
Instruction or task intended to elicit learner production.
P:IQ
Information-seeking question requesting new information.
P:CQ
Clarification question outside a corrective-feedback sequence.
Appendix
Table 7: Instructor prompt subtypes.
Label
Definition
F:EC
Explicit correction that overtly provides the target form.
F:R
Recast that reformulates learner production without explicitly identifying the error.
F:CR
Clarification request following problematic learner production.
F:EL
Elicitation prompting the learner to supply or complete the corrected form.
F:MF
Metalinguistic information about the linguistic problem without directly supplying the correction.
F:CC
Confirmation check of a proposed interpretation or corrected form.
Appendix
Table 8: Instructor feedback subtypes.
Label
Definition
A
Answers a learner question without functioning as corrective feedback.
RN
Reacts to the meaning, content, or emotional aspect of learner production without evaluating linguistic accuracy.
CM
Manages lesson organization, technology, participation, or logistics.
CoM
Regulates conversational flow through minimal expressions such as okay , mhm , or vale .
Appendix
Table 9: Other instructor functions.
Label
Definition
SP
General learner-initiated prompt when a specific subtype cannot be determined reliably.
SP:I
Directs another participant to perform an action.
SP:IQ
Requests new information.
SP:CQ
Requests clarification, repetition, explanation, or lexical assistance.
Appendix
Table 10: Learner-initiated prompt categories.
Label
Definition
R:S
Successful repair that resolves the problem targeted by feedback.
R:IR
Attempted repair that does not fully resolve the targeted problem.
R:Ack
Acknowledges feedback without producing the corrected form.
R:NR
No learner uptake before the interaction moves on.
Appendix
Table 11: Learner uptake and repair outcomes.
Label
Definition
Er:G
One grammatical error involving morphology, syntax, agreement, word order, or another grammatical feature.
Er:L
One incorrect, missing, malformed, or non-Spanish lexical item in otherwise Spanish production.
Er:M
More than one observable grammatical or lexical error.
Er:EU
Substantially English production when Spanish is contextually expected.
Appendix
Table 12: Learner-language error categories.
Distinction
Decision rule
Example
Prompt vs. Feedback
Use P when the instructor initiates new learner production. Use F when responding to, evaluating, or facilitating correction of learner production.
Di una oración. → P:I ; after an error, Di “tiene”. → F:EC .
PR vs. R
Use PR after an instructional prompt and an R subtype within a feedback sequence.
Use F:Pr for positive evaluation of learner performance and RN for reactions to the content or situation described.
S: Estoy cansado. T: Lo siento. → RN .
F:Ack vs. CoM
Use F:Ack when acknowledging learner production as a pedagogical response. Use CoM when the expression primarily regulates conversational flow.
T: Muy bien. → F:Ack or CoM , depending on preceding learner production and context.
CM vs. CoM
Use CM for lesson logistics, technology, participation, or classroom organization. Use CoM for minimal discourse-management expressions.
Voy a compartir mi pantalla. → CM ; Okay. → CoM .
Er:L vs. Er:EU
Use Er:L for an isolated non-Spanish lexical item and Er:EU for substantially English production when Spanish is expected.
Mi mamá lives en California. → Er:L ; My mother lives in California. → Er:EU .
Appendix
Table 13: Key contextual distinctions in the CSLA annotation guidelines.
Gold
Prediction
Score
F:EC
F:EC
100.0
F:EC
F:R
70.0
F:EC
P:I
25.0
F:EC
PR
0.0
F:Pr, P:IQ
F:Pr
50.0
F:Pr, P:IQ
P:IQ, F:Pr
85.0
Appendix
Table 14: Illustrative hierarchical Soft Scores for instructor-role rows. Scores reflect label-family credit, role compatibility, multi-label coverage, and ordering penalties.
Figure 2: SLA-LENS analytical report overview showing anonymized participant information, session-level annotation counts, and guidelines for interpreting the descriptive outputs. All statistics are derived from the annotated transcript without additional LLM inference.
Figure 3: Learner-level descriptive analytics showing approximate word production (top) and error-labeled rows per 100 learner rows (bottom). These measures account for differences in participation but do not independently indicate learner proficiency or language development.