diff --git a/behaverse/utils/BehaverseJsonValidator.py b/behaverse/utils/BehaverseJsonValidator.py
deleted file mode 100644
index 52d4307..0000000
--- a/behaverse/utils/BehaverseJsonValidator.py
+++ /dev/null
@@ -1,56 +0,0 @@
-import jsonschema
-import json
-#import fastjsonschema
-
-class BehaverseJsonValidator():
-    """
-    Loads Behaverse json file from local drive, aggregate json lines into a single
-    array, and validate the content and structure of the events.
-    """
-
-    def __init__(self, json_schema_path: str = None):
-        if json_schema_path is not None:
-            with open(json_schema_path) as f:
-                self.schema = json.load(f)
-
-    @staticmethod
-    def __join_json_lines(src_path):
-        with open(src_path) as f:
-            return f"[{','.join(f.readlines())}]"
-
-    def convert(self, src_path, dest_path):
-        with open(dest_path, "w") as f:
-            f.write(self.__join_json_lines(src_path))
-
-    def validate_json(self, content):
-        """
-        Validates a json object with respect to a predefined schema (json-schema-v7).
-        If json contains errornous content, a validation error will be raised.
-        """
-        assert(self.schema is not None)
-        return jsonschema.validate(content, self.schema)
-
-    def validate_json_file(self, json_path: str):
-        """
-        Loads and validates a json file. Respective validation error will be raised in case of invalid structure.
-        """
-        with open(json_path) as f:
-            content = json.load(f)
-            return self.validate_json(content)
-
-
-if __name__ == "__main__":
-    """
-    Example code showing how to use this class.
-    """
-    original_json_file = "data/samples/nback_demo.json"
-    valid_json_file = "data/samples/nback_demo_v.json"
-    schema_file = "behaverse/validators/nback.schema.json"
-
-    # load and concat json lines
-    #JsonAggregator().convert(original_json_file, valid_json_file)
-
-    # load and validate json lines
-    BehaverseJsonValidator(json_schema_path=schema_file).validate_json_file(valid_json_file)
-
-    print("Good news everyone! Behaverse JSON file is valid!")
\ No newline at end of file

diff --git a/behaverse/utils/BehaverseJsonValidator.py b/behaverse/utils/BehaverseJsonValidator.py
deleted file mode 100644
index 52d4307..0000000
--- a/behaverse/utils/BehaverseJsonValidator.py
+++ /dev/null
@@ -1,56 +0,0 @@
-import jsonschema
-import json
-#import fastjsonschema
-
-class BehaverseJsonValidator():
-    """
-    Loads Behaverse json file from local drive, aggregate json lines into a single
-    array, and validate the content and structure of the events.
-    """
-
-    def __init__(self, json_schema_path: str = None):
-        if json_schema_path is not None:
-            with open(json_schema_path) as f:
-                self.schema = json.load(f)
-
-    @staticmethod
-    def __join_json_lines(src_path):
-        with open(src_path) as f:
-            return f"[{','.join(f.readlines())}]"
-
-    def convert(self, src_path, dest_path):
-        with open(dest_path, "w") as f:
-            f.write(self.__join_json_lines(src_path))
-
-    def validate_json(self, content):
-        """
-        Validates a json object with respect to a predefined schema (json-schema-v7).
-        If json contains errornous content, a validation error will be raised.
-        """
-        assert(self.schema is not None)
-        return jsonschema.validate(content, self.schema)
-
-    def validate_json_file(self, json_path: str):
-        """
-        Loads and validates a json file. Respective validation error will be raised in case of invalid structure.
-        """
-        with open(json_path) as f:
-            content = json.load(f)
-            return self.validate_json(content)
-
-
-if __name__ == "__main__":
-    """
-    Example code showing how to use this class.
-    """
-    original_json_file = "data/samples/nback_demo.json"
-    valid_json_file = "data/samples/nback_demo_v.json"
-    schema_file = "behaverse/validators/nback.schema.json"
-
-    # load and concat json lines
-    #JsonAggregator().convert(original_json_file, valid_json_file)
-
-    # load and validate json lines
-    BehaverseJsonValidator(json_schema_path=schema_file).validate_json_file(valid_json_file)
-
-    print("Good news everyone! Behaverse JSON file is valid!")
\ No newline at end of file
diff --git a/behaverse/validators/BehaverseJsonValidator.py b/behaverse/validators/BehaverseJsonValidator.py
new file mode 100644
index 0000000..52d4307
--- /dev/null
+++ b/behaverse/validators/BehaverseJsonValidator.py
@@ -0,0 +1,56 @@
+import jsonschema
+import json
+#import fastjsonschema
+
+class BehaverseJsonValidator():
+    """
+    Loads Behaverse json file from local drive, aggregate json lines into a single
+    array, and validate the content and structure of the events.
+    """
+
+    def __init__(self, json_schema_path: str = None):
+        if json_schema_path is not None:
+            with open(json_schema_path) as f:
+                self.schema = json.load(f)
+
+    @staticmethod
+    def __join_json_lines(src_path):
+        with open(src_path) as f:
+            return f"[{','.join(f.readlines())}]"
+
+    def convert(self, src_path, dest_path):
+        with open(dest_path, "w") as f:
+            f.write(self.__join_json_lines(src_path))
+
+    def validate_json(self, content):
+        """
+        Validates a json object with respect to a predefined schema (json-schema-v7).
+        If json contains errornous content, a validation error will be raised.
+        """
+        assert(self.schema is not None)
+        return jsonschema.validate(content, self.schema)
+
+    def validate_json_file(self, json_path: str):
+        """
+        Loads and validates a json file. Respective validation error will be raised in case of invalid structure.
+        """
+        with open(json_path) as f:
+            content = json.load(f)
+            return self.validate_json(content)
+
+
+if __name__ == "__main__":
+    """
+    Example code showing how to use this class.
+    """
+    original_json_file = "data/samples/nback_demo.json"
+    valid_json_file = "data/samples/nback_demo_v.json"
+    schema_file = "behaverse/validators/nback.schema.json"
+
+    # load and concat json lines
+    #JsonAggregator().convert(original_json_file, valid_json_file)
+
+    # load and validate json lines
+    BehaverseJsonValidator(json_schema_path=schema_file).validate_json_file(valid_json_file)
+
+    print("Good news everyone! Behaverse JSON file is valid!")
\ No newline at end of file

diff --git a/behaverse/utils/BehaverseJsonValidator.py b/behaverse/utils/BehaverseJsonValidator.py
deleted file mode 100644
index 52d4307..0000000
--- a/behaverse/utils/BehaverseJsonValidator.py
+++ /dev/null
@@ -1,56 +0,0 @@
-import jsonschema
-import json
-#import fastjsonschema
-
-class BehaverseJsonValidator():
-    """
-    Loads Behaverse json file from local drive, aggregate json lines into a single
-    array, and validate the content and structure of the events.
-    """
-
-    def __init__(self, json_schema_path: str = None):
-        if json_schema_path is not None:
-            with open(json_schema_path) as f:
-                self.schema = json.load(f)
-
-    @staticmethod
-    def __join_json_lines(src_path):
-        with open(src_path) as f:
-            return f"[{','.join(f.readlines())}]"
-
-    def convert(self, src_path, dest_path):
-        with open(dest_path, "w") as f:
-            f.write(self.__join_json_lines(src_path))
-
-    def validate_json(self, content):
-        """
-        Validates a json object with respect to a predefined schema (json-schema-v7).
-        If json contains errornous content, a validation error will be raised.
-        """
-        assert(self.schema is not None)
-        return jsonschema.validate(content, self.schema)
-
-    def validate_json_file(self, json_path: str):
-        """
-        Loads and validates a json file. Respective validation error will be raised in case of invalid structure.
-        """
-        with open(json_path) as f:
-            content = json.load(f)
-            return self.validate_json(content)
-
-
-if __name__ == "__main__":
-    """
-    Example code showing how to use this class.
-    """
-    original_json_file = "data/samples/nback_demo.json"
-    valid_json_file = "data/samples/nback_demo_v.json"
-    schema_file = "behaverse/validators/nback.schema.json"
-
-    # load and concat json lines
-    #JsonAggregator().convert(original_json_file, valid_json_file)
-
-    # load and validate json lines
-    BehaverseJsonValidator(json_schema_path=schema_file).validate_json_file(valid_json_file)
-
-    print("Good news everyone! Behaverse JSON file is valid!")
\ No newline at end of file
diff --git a/behaverse/validators/BehaverseJsonValidator.py b/behaverse/validators/BehaverseJsonValidator.py
new file mode 100644
index 0000000..52d4307
--- /dev/null
+++ b/behaverse/validators/BehaverseJsonValidator.py
@@ -0,0 +1,56 @@
+import jsonschema
+import json
+#import fastjsonschema
+
+class BehaverseJsonValidator():
+    """
+    Loads Behaverse json file from local drive, aggregate json lines into a single
+    array, and validate the content and structure of the events.
+    """
+
+    def __init__(self, json_schema_path: str = None):
+        if json_schema_path is not None:
+            with open(json_schema_path) as f:
+                self.schema = json.load(f)
+
+    @staticmethod
+    def __join_json_lines(src_path):
+        with open(src_path) as f:
+            return f"[{','.join(f.readlines())}]"
+
+    def convert(self, src_path, dest_path):
+        with open(dest_path, "w") as f:
+            f.write(self.__join_json_lines(src_path))
+
+    def validate_json(self, content):
+        """
+        Validates a json object with respect to a predefined schema (json-schema-v7).
+        If json contains errornous content, a validation error will be raised.
+        """
+        assert(self.schema is not None)
+        return jsonschema.validate(content, self.schema)
+
+    def validate_json_file(self, json_path: str):
+        """
+        Loads and validates a json file. Respective validation error will be raised in case of invalid structure.
+        """
+        with open(json_path) as f:
+            content = json.load(f)
+            return self.validate_json(content)
+
+
+if __name__ == "__main__":
+    """
+    Example code showing how to use this class.
+    """
+    original_json_file = "data/samples/nback_demo.json"
+    valid_json_file = "data/samples/nback_demo_v.json"
+    schema_file = "behaverse/validators/nback.schema.json"
+
+    # load and concat json lines
+    #JsonAggregator().convert(original_json_file, valid_json_file)
+
+    # load and validate json lines
+    BehaverseJsonValidator(json_schema_path=schema_file).validate_json_file(valid_json_file)
+
+    print("Good news everyone! Behaverse JSON file is valid!")
\ No newline at end of file
diff --git a/behaverse/validators/common_json_validator.Rmd b/behaverse/validators/common_json_validator.Rmd
deleted file mode 100644
index e69de29..0000000
--- a/behaverse/validators/common_json_validator.Rmd
+++ /dev/null

diff --git a/behaverse/utils/BehaverseJsonValidator.py b/behaverse/utils/BehaverseJsonValidator.py
deleted file mode 100644
index 52d4307..0000000
--- a/behaverse/utils/BehaverseJsonValidator.py
+++ /dev/null
@@ -1,56 +0,0 @@
-import jsonschema
-import json
-#import fastjsonschema
-
-class BehaverseJsonValidator():
-    """
-    Loads Behaverse json file from local drive, aggregate json lines into a single
-    array, and validate the content and structure of the events.
-    """
-
-    def __init__(self, json_schema_path: str = None):
-        if json_schema_path is not None:
-            with open(json_schema_path) as f:
-                self.schema = json.load(f)
-
-    @staticmethod
-    def __join_json_lines(src_path):
-        with open(src_path) as f:
-            return f"[{','.join(f.readlines())}]"
-
-    def convert(self, src_path, dest_path):
-        with open(dest_path, "w") as f:
-            f.write(self.__join_json_lines(src_path))
-
-    def validate_json(self, content):
-        """
-        Validates a json object with respect to a predefined schema (json-schema-v7).
-        If json contains errornous content, a validation error will be raised.
-        """
-        assert(self.schema is not None)
-        return jsonschema.validate(content, self.schema)
-
-    def validate_json_file(self, json_path: str):
-        """
-        Loads and validates a json file. Respective validation error will be raised in case of invalid structure.
-        """
-        with open(json_path) as f:
-            content = json.load(f)
-            return self.validate_json(content)
-
-
-if __name__ == "__main__":
-    """
-    Example code showing how to use this class.
-    """
-    original_json_file = "data/samples/nback_demo.json"
-    valid_json_file = "data/samples/nback_demo_v.json"
-    schema_file = "behaverse/validators/nback.schema.json"
-
-    # load and concat json lines
-    #JsonAggregator().convert(original_json_file, valid_json_file)
-
-    # load and validate json lines
-    BehaverseJsonValidator(json_schema_path=schema_file).validate_json_file(valid_json_file)
-
-    print("Good news everyone! Behaverse JSON file is valid!")
\ No newline at end of file
diff --git a/behaverse/validators/BehaverseJsonValidator.py b/behaverse/validators/BehaverseJsonValidator.py
new file mode 100644
index 0000000..52d4307
--- /dev/null
+++ b/behaverse/validators/BehaverseJsonValidator.py
@@ -0,0 +1,56 @@
+import jsonschema
+import json
+#import fastjsonschema
+
+class BehaverseJsonValidator():
+    """
+    Loads Behaverse json file from local drive, aggregate json lines into a single
+    array, and validate the content and structure of the events.
+    """
+
+    def __init__(self, json_schema_path: str = None):
+        if json_schema_path is not None:
+            with open(json_schema_path) as f:
+                self.schema = json.load(f)
+
+    @staticmethod
+    def __join_json_lines(src_path):
+        with open(src_path) as f:
+            return f"[{','.join(f.readlines())}]"
+
+    def convert(self, src_path, dest_path):
+        with open(dest_path, "w") as f:
+            f.write(self.__join_json_lines(src_path))
+
+    def validate_json(self, content):
+        """
+        Validates a json object with respect to a predefined schema (json-schema-v7).
+        If json contains errornous content, a validation error will be raised.
+        """
+        assert(self.schema is not None)
+        return jsonschema.validate(content, self.schema)
+
+    def validate_json_file(self, json_path: str):
+        """
+        Loads and validates a json file. Respective validation error will be raised in case of invalid structure.
+        """
+        with open(json_path) as f:
+            content = json.load(f)
+            return self.validate_json(content)
+
+
+if __name__ == "__main__":
+    """
+    Example code showing how to use this class.
+    """
+    original_json_file = "data/samples/nback_demo.json"
+    valid_json_file = "data/samples/nback_demo_v.json"
+    schema_file = "behaverse/validators/nback.schema.json"
+
+    # load and concat json lines
+    #JsonAggregator().convert(original_json_file, valid_json_file)
+
+    # load and validate json lines
+    BehaverseJsonValidator(json_schema_path=schema_file).validate_json_file(valid_json_file)
+
+    print("Good news everyone! Behaverse JSON file is valid!")
\ No newline at end of file
diff --git a/behaverse/validators/common_json_validator.Rmd b/behaverse/validators/common_json_validator.Rmd
deleted file mode 100644
index e69de29..0000000
--- a/behaverse/validators/common_json_validator.Rmd
+++ /dev/null
diff --git a/behaverse/validators/nback.schema.json b/behaverse/validators/nback.schema.json
index 8a4a215..1feb724 100644
--- a/behaverse/validators/nback.schema.json
+++ b/behaverse/validators/nback.schema.json
@@ -5,23 +5,17 @@
   "description": "A list of events collected using Behaverse N-back task.",
   "type": "array",
   "items": {
-    "$ref": "#/definitions/NbackEvent"
+    "$ref": "#/definitions/Event"
   },
   "definitions": {
-    "NbackEvent":{
-      "title": "A Single N-back Event",
+    "Event":{
+      "title": "A N-back Event",
       "type": "object",
       "additionalProperties": false,
       "properties": {
-        "base": {
-          "$ref": "#/definitions/Base"
-        },
-        "types": {
-          "$ref": "#/definitions/Types"
-        },
-        "custom": {
-          "$ref": "#/definitions/Custom"
-        }
+        "base": { "$ref": "#/definitions/Base" },
+        "types": { "$ref": "#/definitions/Types" },
+        "custom": { "$ref": "#/definitions/Custom" }
       },
       "required": ["base", "types", "custom"]
     },
@@ -93,7 +87,9 @@
         },
         {
           "if": {
-            "properties": {"types": {"enum": ["NBack.BlockStart"]}}
+            "properties": {
+              "types": {"enum": ["NBack.BlockStart"]}
+            }
           },
           "then": {
             "required": ["id", "type"]
@@ -101,6 +97,39 @@
         },
         {
           "if": {
+            "properties": {"types": {"enum": ["NBack.BlockEnd"]}},
+            "$comment": "jq command to extract required parameters: [.[] | select(.types | .[] | contains(\"NBack.BlockEnd\")) | .custom | keys] | unique | .[][]"
+          },
+          "then": {
+            "required": ["id","type","name","seed","accuracy","hitCount","missCount", "falseAlaram", "correctRejectionCount", "timeOutCount"]
+          }
+        },
+        {
+          "if": {
+            "properties": {"types": {"enum": ["NBack.TaskEnd"]}}
+          },
+          "then": {
+            "required": []
+          }
+        },
+        {
+          "if": {
+            "properties": {"types": {"enum": ["NBack.TrialEnd"]}}
+          },
+          "then": {
+            "required": []
+          }
+        },
+        {
+          "if": {
+            "properties": {"types": {"enum": ["NBack.TrialStart"]}}
+          },
+          "then": {
+            "required": ["id", "seed"]
+          }
+        },
+        {
+          "if": {
             "properties": {"types": {"enum": ["NBack.MatchingButtonClick"]}}
           },
           "then": {
@@ -118,6 +147,16 @@
         "y": {"type": "number"}
       },
       "required": ["x", "y"]
+    },
+    "InstructionCustom": {
+      "title": "Custom element for instruction blocks",
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "id": {"type": "number"},
+        "type": {"type": "string", "enum": ["Instruction"]}
+      },
+      "required": ["id", "type"]
     }
   }
 }
\ No newline at end of file

diff --git a/behaverse/utils/BehaverseJsonValidator.py b/behaverse/utils/BehaverseJsonValidator.py
deleted file mode 100644
index 52d4307..0000000
--- a/behaverse/utils/BehaverseJsonValidator.py
+++ /dev/null
@@ -1,56 +0,0 @@
-import jsonschema
-import json
-#import fastjsonschema
-
-class BehaverseJsonValidator():
-    """
-    Loads Behaverse json file from local drive, aggregate json lines into a single
-    array, and validate the content and structure of the events.
-    """
-
-    def __init__(self, json_schema_path: str = None):
-        if json_schema_path is not None:
-            with open(json_schema_path) as f:
-                self.schema = json.load(f)
-
-    @staticmethod
-    def __join_json_lines(src_path):
-        with open(src_path) as f:
-            return f"[{','.join(f.readlines())}]"
-
-    def convert(self, src_path, dest_path):
-        with open(dest_path, "w") as f:
-            f.write(self.__join_json_lines(src_path))
-
-    def validate_json(self, content):
-        """
-        Validates a json object with respect to a predefined schema (json-schema-v7).
-        If json contains errornous content, a validation error will be raised.
-        """
-        assert(self.schema is not None)
-        return jsonschema.validate(content, self.schema)
-
-    def validate_json_file(self, json_path: str):
-        """
-        Loads and validates a json file. Respective validation error will be raised in case of invalid structure.
-        """
-        with open(json_path) as f:
-            content = json.load(f)
-            return self.validate_json(content)
-
-
-if __name__ == "__main__":
-    """
-    Example code showing how to use this class.
-    """
-    original_json_file = "data/samples/nback_demo.json"
-    valid_json_file = "data/samples/nback_demo_v.json"
-    schema_file = "behaverse/validators/nback.schema.json"
-
-    # load and concat json lines
-    #JsonAggregator().convert(original_json_file, valid_json_file)
-
-    # load and validate json lines
-    BehaverseJsonValidator(json_schema_path=schema_file).validate_json_file(valid_json_file)
-
-    print("Good news everyone! Behaverse JSON file is valid!")
\ No newline at end of file
diff --git a/behaverse/validators/BehaverseJsonValidator.py b/behaverse/validators/BehaverseJsonValidator.py
new file mode 100644
index 0000000..52d4307
--- /dev/null
+++ b/behaverse/validators/BehaverseJsonValidator.py
@@ -0,0 +1,56 @@
+import jsonschema
+import json
+#import fastjsonschema
+
+class BehaverseJsonValidator():
+    """
+    Loads Behaverse json file from local drive, aggregate json lines into a single
+    array, and validate the content and structure of the events.
+    """
+
+    def __init__(self, json_schema_path: str = None):
+        if json_schema_path is not None:
+            with open(json_schema_path) as f:
+                self.schema = json.load(f)
+
+    @staticmethod
+    def __join_json_lines(src_path):
+        with open(src_path) as f:
+            return f"[{','.join(f.readlines())}]"
+
+    def convert(self, src_path, dest_path):
+        with open(dest_path, "w") as f:
+            f.write(self.__join_json_lines(src_path))
+
+    def validate_json(self, content):
+        """
+        Validates a json object with respect to a predefined schema (json-schema-v7).
+        If json contains errornous content, a validation error will be raised.
+        """
+        assert(self.schema is not None)
+        return jsonschema.validate(content, self.schema)
+
+    def validate_json_file(self, json_path: str):
+        """
+        Loads and validates a json file. Respective validation error will be raised in case of invalid structure.
+        """
+        with open(json_path) as f:
+            content = json.load(f)
+            return self.validate_json(content)
+
+
+if __name__ == "__main__":
+    """
+    Example code showing how to use this class.
+    """
+    original_json_file = "data/samples/nback_demo.json"
+    valid_json_file = "data/samples/nback_demo_v.json"
+    schema_file = "behaverse/validators/nback.schema.json"
+
+    # load and concat json lines
+    #JsonAggregator().convert(original_json_file, valid_json_file)
+
+    # load and validate json lines
+    BehaverseJsonValidator(json_schema_path=schema_file).validate_json_file(valid_json_file)
+
+    print("Good news everyone! Behaverse JSON file is valid!")
\ No newline at end of file
diff --git a/behaverse/validators/common_json_validator.Rmd b/behaverse/validators/common_json_validator.Rmd
deleted file mode 100644
index e69de29..0000000
--- a/behaverse/validators/common_json_validator.Rmd
+++ /dev/null
diff --git a/behaverse/validators/nback.schema.json b/behaverse/validators/nback.schema.json
index 8a4a215..1feb724 100644
--- a/behaverse/validators/nback.schema.json
+++ b/behaverse/validators/nback.schema.json
@@ -5,23 +5,17 @@
   "description": "A list of events collected using Behaverse N-back task.",
   "type": "array",
   "items": {
-    "$ref": "#/definitions/NbackEvent"
+    "$ref": "#/definitions/Event"
   },
   "definitions": {
-    "NbackEvent":{
-      "title": "A Single N-back Event",
+    "Event":{
+      "title": "A N-back Event",
       "type": "object",
       "additionalProperties": false,
       "properties": {
-        "base": {
-          "$ref": "#/definitions/Base"
-        },
-        "types": {
-          "$ref": "#/definitions/Types"
-        },
-        "custom": {
-          "$ref": "#/definitions/Custom"
-        }
+        "base": { "$ref": "#/definitions/Base" },
+        "types": { "$ref": "#/definitions/Types" },
+        "custom": { "$ref": "#/definitions/Custom" }
       },
       "required": ["base", "types", "custom"]
     },
@@ -93,7 +87,9 @@
         },
         {
           "if": {
-            "properties": {"types": {"enum": ["NBack.BlockStart"]}}
+            "properties": {
+              "types": {"enum": ["NBack.BlockStart"]}
+            }
           },
           "then": {
             "required": ["id", "type"]
@@ -101,6 +97,39 @@
         },
         {
           "if": {
+            "properties": {"types": {"enum": ["NBack.BlockEnd"]}},
+            "$comment": "jq command to extract required parameters: [.[] | select(.types | .[] | contains(\"NBack.BlockEnd\")) | .custom | keys] | unique | .[][]"
+          },
+          "then": {
+            "required": ["id","type","name","seed","accuracy","hitCount","missCount", "falseAlaram", "correctRejectionCount", "timeOutCount"]
+          }
+        },
+        {
+          "if": {
+            "properties": {"types": {"enum": ["NBack.TaskEnd"]}}
+          },
+          "then": {
+            "required": []
+          }
+        },
+        {
+          "if": {
+            "properties": {"types": {"enum": ["NBack.TrialEnd"]}}
+          },
+          "then": {
+            "required": []
+          }
+        },
+        {
+          "if": {
+            "properties": {"types": {"enum": ["NBack.TrialStart"]}}
+          },
+          "then": {
+            "required": ["id", "seed"]
+          }
+        },
+        {
+          "if": {
             "properties": {"types": {"enum": ["NBack.MatchingButtonClick"]}}
           },
           "then": {
@@ -118,6 +147,16 @@
         "y": {"type": "number"}
       },
       "required": ["x", "y"]
+    },
+    "InstructionCustom": {
+      "title": "Custom element for instruction blocks",
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "id": {"type": "number"},
+        "type": {"type": "string", "enum": ["Instruction"]}
+      },
+      "required": ["id", "type"]
     }
   }
 }
\ No newline at end of file
diff --git a/behaverse/validators/nback_json_validator.Rmd b/behaverse/validators/nback_json_validator.Rmd
new file mode 100644
index 0000000..76c8a4a
--- /dev/null
+++ b/behaverse/validators/nback_json_validator.Rmd
@@ -0,0 +1,85 @@
+---
+title: "Validate Behaverse Sample Data Files"
+author: "Morteza Ansarinia"
+date: "Nov 26, 2019"
+output: 
+  html_document: 
+    highlight: espresso
+---
+
+```{r setup, include=FALSE}
+# TODO: change the current directory to where `data` and `behaverse/validators` are available.
+knitr::opts_knit$set(root.dir = "~/workspace/notebooks/")
+
+knitr::opts_chunk$set(echo = TRUE)
+
+library(reticulate)
+use_condaenv("miniconda3", conda = "auto", required = T)
+```
+
+The following code demonstrates how to validate the content of a sample json file generated by Behaverse.
+
+TODO: BUILD?
+
+```{python}
+import jsonschema
+import json
+#import fastjsonschema
+
+class BehaverseJsonValidator():
+    """
+    Loads Behaverse json file from local drive, aggregate json lines into a single
+    array, and validate the content and structure of the events.
+    """
+
+    def __init__(self, json_schema_path: str = None):
+        if json_schema_path is not None:
+            with open(json_schema_path) as f:
+                self.schema = json.load(f)
+
+    @staticmethod
+    def __join_json_lines(src_path):
+        with open(src_path) as f:
+            return f"[{','.join(f.readlines())}]"
+
+    def convert(self, src_path, dest_path):
+        with open(dest_path, "w") as f:
+            f.write(self.__join_json_lines(src_path))
+
+    def validate_json(self, content):
+        """
+        Validates a json object with respect to a predefined schema (json-schema-v7).
+        If json contains errornous content, a validation error will be raised.
+        """
+        assert(self.schema is not None)
+        return jsonschema.validate(content, self.schema)
+
+    def validate_json_file(self, json_path: str):
+        """
+        Loads and validates a json file. Respective validation error will be raised in case of invalid structure.
+        """
+        with open(json_path) as f:
+            content = json.load(f)
+            return self.validate_json(content)
+
+```
+
+This code first concats all json lines and produces a single json array, and then confirms the validity of the json file according to a provided schema. This schema contains rules to validate content, structures, conditional structures (e.g., `custom` metadata), and integrity of the stored fields.
+
+TODO: list all concerns that is being tested in a bullet list.
+
+
+```{python}
+import os
+original_json_file = "data/samples/nback_demo.json"
+valid_json_file = "data/samples/nback_demo_v.json"
+schema_file = "behaverse/validators/nback.schema.json"
+
+# load and concat json lines
+#BehaverseJsonValidator().convert(original_json_file, valid_json_file)
+
+# load and validate json lines
+BehaverseJsonValidator(json_schema_path=schema_file).validate_json_file(valid_json_file)
+
+print("Good news everyone! Behaverse JSON file is valid!")
+```