{
  "id": "programming.variables.assignment-is-equation",
  "uri": "https://open-misconceptions.github.io/miscon-data/m/programming.variables.assignment-is-equation",
  "uuid": "1d678f7e-ebf2-49bf-979f-eb433148cc0e",
  "version": "0.1.1",
  "status": "draft",
  "trust": "low",
  "title": "Assignment states an equation",
  "statement": "The equals sign in an assignment states that the two sides are equal, as in algebra, so x = x + 1 is a contradiction and a = b and b = a mean the same thing.",
  "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 an assignment whose right-hand side uses the variable being assigned",
      "signature": "declares the statement impossible or leaves the variable unchanged",
      "example": {
        "item": "x = 5\nx = x + 1\nWhat is x?",
        "expected": "6",
        "response": "'Impossible, x can't equal x + 1' (or 5)"
      }
    },
    {
      "item_shape": "trace an assignment with the variables in the 'wrong' order",
      "signature": "treats a = b as also setting b from a, or asks which one changes",
      "example": {
        "item": "a = 1\nb = 2\na = b\nWhat are a and b?",
        "expected": "a is 2, b is 2",
        "response": "a is 1, b is 1 (or 'they are now the same variable')"
      }
    }
  ],
  "discriminators": {
    "vs_slip": "Consistent across items; the learner uses the words 'equals' or 'is the same as' and objects to x = x + 1. A slip is a wrong final value with an otherwise correct trace.",
    "vs": {
      "programming.variables.assignment-links-variables": "Linkers accept a = b as directional but expect later changes to b to show up in a; equation believers object at the moment of assignment.",
      "programming.variables.assignment-moves-value": "Movers empty the source variable; equation believers keep both sides equal."
    }
  },
  "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-moves-value"
    ]
  },
  "alignments": [
    {
      "scheme": "progmiscon",
      "code": "Java/AssignCompares",
      "uri": "https://progmiscon.org/misconceptions/Java/AssignCompares",
      "relation": "close-match",
      "note": "progmiscon's entry covers reading = as a comparison; this record covers the underlying algebraic reading."
    }
  ],
  "provenance": {
    "sources": [
      {
        "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",
        "note": "Notional machine difficulties; the equals sign carrying its mathematical meaning."
      },
      {
        "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"
      },
      {
        "type": "paper",
        "citation": "Qian, Y., & Lehman, J. (2017). Students' misconceptions and other difficulties in introductory programming: A literature review. ACM Transactions on Computing Education, 18(1), Article 1.",
        "doi": "10.1145/3077618"
      },
      {
        "type": "inventory",
        "citation": "Chiodini, L., Moreno Santos, I., Gallidabino, A., Tafliovich, A., Santos, A. L., & Hauswirth, M. (2021). A curated inventory of programming language misconceptions. In Proceedings of the 26th ACM Conference on Innovation and Technology in Computer Science Education (ITiCSE '21), 380-386.",
        "doi": "10.1145/3430665.3456343",
        "url": "https://progmiscon.org/",
        "note": "Inventory consulted for the misconception name and scope only; progmiscon publishes no licence for its text, so Open Misconceptions' statements and examples are written independently."
      }
    ],
    "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"
}