We propose a methodology for the multimodal semantic annotation of classroom interactions that takes interactional canvases and semantic frames as its core analytical categories. The approach enables the systematic recording of semantic correlations among interactants, communicative modes, and material supports involved in situated meaning-making processes. The methodology encodes participant perspective by relying on the temporal alignment of multiple video recordings of the same instructional event captured from different viewpoints, allowing for the representation of how meaning construction unfolds across perceptual and interactional positions. To operationalize the proposal, we introduce an annotation tool that implements the scheme and supports the integration of multimodal data streams within a unified semantic representation framework. We conclude by discussing the limitations of the current proposal and the possibilities for extending it to other interactional settings.