diff --git a/in2lambda/api/response_area.py b/in2lambda/api/response_area.py
index 430dcac..feda205 100644
--- a/in2lambda/api/response_area.py
+++ b/in2lambda/api/response_area.py
@@ -120,6 +120,10 @@ def _grade_params(self) -> Optional[dict[str, Any]]:
         """The parameters sent to the evaluation function."""
         return self.grade_params
 
+    def _serial(self, value: Any) -> Any:
+        """An answer or test payload as Lambda Feedback stores it."""
+        return value
+
 
 @dataclass(kw_only=True)
 class _Maths(ResponseArea):
@@ -185,6 +189,14 @@ class Boolean(ResponseArea):
     response_type: ClassVar[str] = "BOOLEAN"
     answer: bool = False
 
+    # Lambda Feedback stores the answer, and sends the response, as 1 or 0, and
+    # isExactEqual compares them as strings.
+    def _serial(self, value: Any) -> Any:
+        return int(value) if isinstance(value, bool) else value
+
+    def _grade_params(self) -> Optional[dict[str, Any]]:
+        return {"type": "str", **(self.grade_params or {})}
+
 
 @dataclass(kw_only=True)
 class MultipleChoice(ResponseArea):
diff --git a/in2lambda/json_convert/json_convert.py b/in2lambda/json_convert/json_convert.py
index 270ef38..186ee28 100644
--- a/in2lambda/json_convert/json_convert.py
+++ b/in2lambda/json_convert/json_convert.py
@@ -71,7 +71,7 @@ def _response_area_to_json(area: ResponseArea, order: int) -> dict[str, Any]:
         "tests": [
             {
                 "id": test.id,
-                "payload": test.payload,
+                "payload": area._serial(test.payload),
                 "expectedResponse": {"isCorrect": test.is_correct},
             }
             for test in area.tests
@@ -80,7 +80,7 @@ def _response_area_to_json(area: ResponseArea, order: int) -> dict[str, Any]:
         "response": {
             "responseInput": {
                 "responseType": area.response_type,
-                "answer": area.answer,
+                "answer": area._serial(area.answer),
                 "config": area._config(),
             }
         },
diff --git a/tests/test_boolean.py b/tests/test_boolean.py
new file mode 100644
index 0000000..51a8560
--- /dev/null
+++ b/tests/test_boolean.py
@@ -0,0 +1,10 @@
+"""A Boolean area is written as Lambda Feedback's own teacher test sends it."""
+
+from in2lambda.api.response_area import Boolean
+from in2lambda.json_convert.json_convert import _response_area_to_json
+
+
+def test_a_boolean_answer_is_written_as_a_number_compared_as_a_string() -> None:
+    area = _response_area_to_json(Boolean(answer=True), 0)
+    assert area["response"]["responseInput"]["answer"] == 1
+    assert area["gradeParams"] == {"type": "str"}