Fix the demo for the schools (#8879)

* Fix the demo for the schools

* Fix for the demo

https://github.com/frappe/erpnext/issues/6347
diff --git a/erpnext/demo/data/grading_scale.json b/erpnext/demo/data/grading_scale.json
new file mode 100644
index 0000000..0760919
--- /dev/null
+++ b/erpnext/demo/data/grading_scale.json
@@ -0,0 +1,17 @@
+[
+	{
+		"doctype": "Grading Scale",
+		"grading_scale_name": "Standard Grading",
+		"description": "Standard Grading Scale",
+		"intervals": [
+			{"threshold": 100.0, "grade_code": "A", "grade_description": "Excellent"},
+			{"threshold": 89.9, "grade_code": "B+", "grade_description": "Close to Excellence"},
+			{"threshold": 80.0, "grade_code": "B", "grade_description": "Good"},
+			{"threshold": 69.9, "grade_code": "C+", "grade_description": "Almost Good"},
+			{"threshold": 60.0, "grade_code": "C", "grade_description": "Average"},
+			{"threshold": 50.0, "grade_code": "D+", "grade_description": "Have to Work"},
+			{"threshold": 40.0, "grade_code": "D", "grade_description": "Not met Baseline Expectations"},
+			{"threshold": 0.0, "grade_code": "F", "grade_description": "Have to work a lot"}
+		]
+	}
+]
\ No newline at end of file