{
  "id": "programming.variables.assignment-moves-value",
  "uri": "https://open-misconceptions.github.io/miscon-data/m/programming.variables.assignment-moves-value",
  "uuid": "55c0374e-b4f9-4b70-aef3-8d020d2c99c1",
  "version": "0.1.1",
  "status": "draft",
  "trust": "low",
  "title": "Assignment moves the value out of the source",
  "statement": "Assigning a = b moves the value from b into a, so b is empty or zero afterwards.",
  "kind": "misapplied-analogy",
  "domain": "programming.variables",
  "about": [
    {
      "scheme": "Miscon",
      "uri": "https://open-misconceptions.github.io/miscon-data/c/programming.variables.assignment"
    }
  ],
  "level_band": [
    "secondary",
    "undergraduate",
    "adult"
  ],
  "locale": "en",
  "evidence_patterns": [
    {
      "item_shape": "trace the source variable after an assignment",
      "signature": "reports the source as empty, zero or undefined",
      "example": {
        "item": "b = 4\na = b\nWhat is b?",
        "expected": "4",
        "response": "0 (or 'nothing')"
      }
    }
  ],
  "discriminators": {
    "vs_slip": "Consistent across items; the learner explains that the value 'went into' the other variable. A slip does not empty the source.",
    "vs": {
      "programming.variables.assignment-links-variables": "Linkers keep both variables and couple them; movers empty the source."
    }
  },
  "relations": {
    "conflicts_with": [
      {
        "external": "https://open-misconceptions.github.io/miscon-data/c/programming.variables.assignment",
        "label": "Assignment copies a value into a variable at one moment"
      }
    ],
    "resolved_by": [
      {
        "external": "https://open-misconceptions.github.io/miscon-data/c/programming.variables.assignment",
        "label": "Assignment copies a value into a variable at one moment"
      }
    ],
    "confusable_with": [
      "programming.variables.assignment-links-variables",
      "programming.variables.assignment-is-equation"
    ]
  },
  "provenance": {
    "sources": [
      {
        "type": "paper",
        "citation": "Bayman, P., & Mayer, R. E. (1983). A diagnosis of beginning programmers' misconceptions of BASIC programming statements. Communications of the ACM, 26(9), 677-679.",
        "doi": "10.1145/358172.358408",
        "note": "LET statements understood as moving a value."
      },
      {
        "type": "paper",
        "citation": "du Boulay, B. (1986). Some difficulties of learning to program. Journal of Educational Computing Research, 2(1), 57-73.",
        "doi": "10.2190/3LFX-9RRF-67T8-UVK9"
      },
      {
        "type": "book",
        "citation": "Sorva, J. (2012). Visual Program Simulation in Introductory Programming Education (Doctoral dissertation, Aalto University). Appendix A catalogues introductory programming misconceptions from the literature.",
        "url": "https://aaltodoc.aalto.fi/handle/123456789/3534"
      }
    ],
    "origin": "llm-drafted",
    "notes": "Drafted from the cited literature for the Open Misconceptions seed pack; statement, examples and discriminators are original text. Awaiting maintainer review."
  },
  "history": {
    "changelog": [
      {
        "version": "0.1.1",
        "date": "2026-09-05",
        "change": "Schema 0.2 migration: about/alignments carry a free-string scheme (corestandards.org URLs relabelled CCSS where present); trust computed from reviews[] (none yet, so low); no change to the statement or evidence."
      }
    ]
  },
  "license": "CC-BY-4.0"
}