diff --git a/exercises/practice/grade-school/.meta/example.lua b/exercises/practice/grade-school/.meta/example.lua
index d4d7ba17..68983ce7 100644
--- a/exercises/practice/grade-school/.meta/example.lua
+++ b/exercises/practice/grade-school/.meta/example.lua
@@ -6,23 +6,36 @@ function School:new()
 end
 
 function School:roster()
-  return self.db
+  local roster = {}
+  for _, grade in pairs(self.db) do
+    for _, student in ipairs(grade) do
+      table.insert(roster, student)
+    end
+  end
+  return roster
 end
 
 function School:add(name, grade)
+  for _, grade in pairs(self.db) do
+    for _, student in ipairs(grade) do
+      if student == name then
+        return false
+      end
+    end
+  end
+
   if self.db[grade] then
     table.insert(self.db[grade], name)
     table.sort(self.db[grade])
   else
     self.db[grade] = { name }
   end
+
+  return true
 end
 
 function School:grade(grade)
-  if self.db[grade] then
-    return self.db[grade]
-  end
-  return {}
+  return self.db[grade] or {}
 end
 
 return School
diff --git a/exercises/practice/grade-school/.meta/spec_generator.lua b/exercises/practice/grade-school/.meta/spec_generator.lua
new file mode 100644
index 00000000..ed1e930b
--- /dev/null
+++ b/exercises/practice/grade-school/.meta/spec_generator.lua
@@ -0,0 +1,46 @@
+local function map(t, f)
+  local mapped = {}
+  for i, v in ipairs(t) do
+    mapped[i] = f(v)
+  end
+  return mapped
+end
+
+local function stringify(x)
+  return ("'%s'"):format(x)
+end
+
+return {
+  module_name = 'School',
+
+  generate_test = function(case)
+    local lines = { 'local school = School:new()' }
+
+    if case.property == 'grade' or case.property == 'roster' then
+      for _, input in ipairs(case.input.students) do
+        local student, grade = table.unpack(input)
+        table.insert(lines, ('school:add(%s, %d)'):format(stringify(student), grade))
+      end
+      table.insert(lines,
+                   ('assert.are.same({ %s }, school:%s(%s))'):format(table.concat(map(case.expected, stringify), ', '),
+                                                                     case.property, case.input.desiredGrade or ''))
+    elseif case.property == 'add' then
+      for i, input in ipairs(case.input.students) do
+        local student, grade = table.unpack(input)
+        local expected
+        do
+          if type(case.expected) == 'table' then
+            expected = case.expected[i]
+          else
+            expected = case.expected
+          end
+        end
+        table.insert(lines, ('assert.is_%s(school:add(%s, %d))'):format(expected, stringify(student), grade))
+      end
+    else
+      error("Unknown property: " .. case.property)
+    end
+
+    return table.concat(lines, '\n')
+  end
+}
diff --git a/exercises/practice/grade-school/.meta/tests.toml b/exercises/practice/grade-school/.meta/tests.toml
index eada129d..50c9e2e5 100644
--- a/exercises/practice/grade-school/.meta/tests.toml
+++ b/exercises/practice/grade-school/.meta/tests.toml
@@ -1,24 +1,86 @@
-# This is an auto-generated file. Regular comments will be removed when this
-# file is regenerated. Regenerating will not touch any manually added keys,
-# so comments can be added in a "comment" key.
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[a3f0fb58-f240-4723-8ddc-e644666b85cc]
+description = "Roster is empty when no student is added"
+
+[9337267f-7793-4b90-9b4a-8e3978408824]
+description = "Add a student"
 
 [6d0a30e4-1b4e-472e-8e20-c41702125667]
-description = "Adding a student adds them to the sorted roster"
+description = "Student is added to the roster"
+
+[73c3ca75-0c16-40d7-82f5-ed8fe17a8e4a]
+description = "Adding multiple students in the same grade in the roster"
 
 [233be705-dd58-4968-889d-fb3c7954c9cc]
-description = "Adding more student adds them to the sorted roster"
+description = "Multiple students in the same grade are added to the roster"
+
+[87c871c1-6bde-4413-9c44-73d59a259d83]
+description = "Cannot add student to same grade in the roster more than once"
+
+[c125dab7-2a53-492f-a99a-56ad511940d8]
+description = "A student can't be in two different grades"
+include = false
+
+[a0c7b9b8-0e89-47f8-8b4a-c50f885e79d1]
+description = "A student can only be added to the same grade in the roster once"
+include = false
+reimplements = "c125dab7-2a53-492f-a99a-56ad511940d8"
+
+[d7982c4f-1602-49f6-a651-620f2614243a]
+description = "Student not added to same grade in the roster more than once"
+reimplements = "a0c7b9b8-0e89-47f8-8b4a-c50f885e79d1"
+
+[e70d5d8f-43a9-41fd-94a4-1ea0fa338056]
+description = "Adding students in multiple grades"
 
 [75a51579-d1d7-407c-a2f8-2166e984e8ab]
-description = "Adding students to different grades adds them to the same sorted roster"
+description = "Students in multiple grades are added to the roster"
 
-[a3f0fb58-f240-4723-8ddc-e644666b85cc]
-description = "Roster returns an empty list if there are no students enrolled"
+[7df542f1-57ce-433c-b249-ff77028ec479]
+description = "Cannot add same student to multiple grades in the roster"
 
-[180a8ff9-5b94-43fc-9db1-d46b4a8c93b6]
-description = "Student names with grades are displayed in the same sorted roster"
+[6a03b61e-1211-4783-a3cc-fc7f773fba3f]
+description = "A student cannot be added to more than one grade in the sorted roster"
+include = false
+reimplements = "c125dab7-2a53-492f-a99a-56ad511940d8"
 
-[1bfbcef1-e4a3-49e8-8d22-f6f9f386187e]
-description = "Grade returns the students in that grade in alphabetical order"
+[c7ec1c5e-9ab7-4d3b-be5c-29f2f7a237c5]
+description = "Student not added to multiple grades in the roster"
+reimplements = "6a03b61e-1211-4783-a3cc-fc7f773fba3f"
+
+[d9af4f19-1ba1-48e7-94d0-dabda4e5aba6]
+description = "Students are sorted by grades in the roster"
+
+[d9fb5bea-f5aa-4524-9d61-c158d8906807]
+description = "Students are sorted by name in the roster"
+
+[180a8ff9-5b94-43fc-9db1-d46b4a8c93b6]
+description = "Students are sorted by grades and then by name in the roster"
 
 [5e67aa3c-a3c6-4407-a183-d8fe59cd1630]
-description = "Grade returns an empty list if there are no students in that grade"
+description = "Grade is empty if no students in the roster"
+
+[1e0cf06b-26e0-4526-af2d-a2e2df6a51d6]
+description = "Grade is empty if no students in that grade"
+
+[2bfc697c-adf2-4b65-8d0f-c46e085f796e]
+description = "Student not added to same grade more than once"
+
+[66c8e141-68ab-4a04-a15a-c28bc07fe6b9]
+description = "Student not added to multiple grades"
+
+[c9c1fc2f-42e0-4d2c-b361-99271f03eda7]
+description = "Student not added to other grade for multiple grades"
+
+[1bfbcef1-e4a3-49e8-8d22-f6f9f386187e]
+description = "Students are sorted by name in a grade"
diff --git a/exercises/practice/grade-school/grade-school_spec.lua b/exercises/practice/grade-school/grade-school_spec.lua
index c926bc8f..55bbd123 100644
--- a/exercises/practice/grade-school/grade-school_spec.lua
+++ b/exercises/practice/grade-school/grade-school_spec.lua
@@ -1,65 +1,158 @@
 local School = require('grade-school')
 
 describe('grade-school', function()
-  it('a new school has an empty roster', function()
+  it('roster is empty when no student is added', function()
     local school = School:new()
-    local expected = {}
-    local result = school:roster()
-    assert.are.same(expected, result)
+    assert.are.same({}, school:roster())
   end)
 
-  it('adding a student adds them to the roster for the given grade', function()
+  it('add a student', function()
+    local school = School:new()
+    assert.is_true(school:add('Aimee', 2))
+  end)
+
+  it('student is added to the roster', function()
     local school = School:new()
     school:add('Aimee', 2)
-    local expected = { [2] = { 'Aimee' } }
-    local result = school:roster()
-    assert.are.same(expected, result)
+    assert.are.same({ 'Aimee' }, school:roster())
+  end)
+
+  it('adding multiple students in the same grade in the roster', function()
+    local school = School:new()
+    assert.is_true(school:add('Blair', 2))
+    assert.is_true(school:add('James', 2))
+    assert.is_true(school:add('Paul', 2))
+  end)
+
+  it('multiple students in the same grade are added to the roster', function()
+    local school = School:new()
+    school:add('Blair', 2)
+    school:add('James', 2)
+    school:add('Paul', 2)
+    assert.are.same({ 'Blair', 'James', 'Paul' }, school:roster())
+  end)
+
+  it('cannot add student to same grade in the roster more than once', function()
+    local school = School:new()
+    assert.is_true(school:add('Blair', 2))
+    assert.is_true(school:add('James', 2))
+    assert.is_false(school:add('James', 2))
+    assert.is_true(school:add('Paul', 2))
   end)
 
-  it('adding more students to the same grade adds them to the roster', function()
+  it('student not added to same grade in the roster more than once', function()
     local school = School:new()
     school:add('Blair', 2)
     school:add('James', 2)
+    school:add('James', 2)
     school:add('Paul', 2)
-    local expected = { [2] = { 'Blair', 'James', 'Paul' } }
-    local result = school:roster()
-    assert.are.same(expected, result)
+    assert.are.same({ 'Blair', 'James', 'Paul' }, school:roster())
+  end)
+
+  it('adding students in multiple grades', function()
+    local school = School:new()
+    assert.is_true(school:add('Chelsea', 3))
+    assert.is_true(school:add('Logan', 7))
   end)
 
-  it('adding students to different grades adds them to the roster', function()
+  it('students in multiple grades are added to the roster', function()
     local school = School:new()
     school:add('Chelsea', 3)
     school:add('Logan', 7)
-    local expected = { [3] = { 'Chelsea' }, [7] = { 'Logan' } }
-    local result = school:roster()
-    assert.are.same(expected, result)
+    assert.are.same({ 'Chelsea', 'Logan' }, school:roster())
   end)
 
-  it('grade returns the students in that grade in alphabetical order', function()
+  it('cannot add same student to multiple grades in the roster', function()
     local school = School:new()
-    school:add('Franklin', 5)
-    school:add('Bradley', 5)
-    school:add('Jeff', 1)
-    local expected = { 'Bradley', 'Franklin' }
-    local result = school:grade(5)
-    assert.are.same(expected, result)
+    assert.is_true(school:add('Blair', 2))
+    assert.is_true(school:add('James', 2))
+    assert.is_false(school:add('James', 3))
+    assert.is_true(school:add('Paul', 3))
+  end)
+
+  it('student not added to multiple grades in the roster', function()
+    local school = School:new()
+    school:add('Blair', 2)
+    school:add('James', 2)
+    school:add('James', 3)
+    school:add('Paul', 3)
+    assert.are.same({ 'Blair', 'James', 'Paul' }, school:roster())
+  end)
+
+  it('students are sorted by grades in the roster', function()
+    local school = School:new()
+    school:add('Jim', 3)
+    school:add('Peter', 2)
+    school:add('Anna', 1)
+    assert.are.same({ 'Anna', 'Peter', 'Jim' }, school:roster())
   end)
 
-  it('grade returns an empty array if there are no students in that grade', function()
+  it('students are sorted by name in the roster', function()
     local school = School:new()
-    local result = school:grade(1)
-    local expected = {}
-    assert.are.same(expected, result)
+    school:add('Peter', 2)
+    school:add('Zoe', 2)
+    school:add('Alex', 2)
+    assert.are.same({ 'Alex', 'Peter', 'Zoe' }, school:roster())
   end)
 
-  it('the students names in each grade in the roster are sorted', function()
+  it('students are sorted by grades and then by name in the roster', function()
     local school = School:new()
-    school:add('Jennifer', 4)
-    school:add('Kareem', 6)
-    school:add('Christopher', 4)
-    school:add('Kyle', 3)
-    local expected = { [3] = { 'Kyle' }, [4] = { 'Christopher', 'Jennifer' }, [6] = { 'Kareem' } }
-    local result = school:roster()
-    assert.are.same(expected, result)
+    school:add('Peter', 2)
+    school:add('Anna', 1)
+    school:add('Barb', 1)
+    school:add('Zoe', 2)
+    school:add('Alex', 2)
+    school:add('Jim', 3)
+    school:add('Charlie', 1)
+    assert.are.same({ 'Anna', 'Barb', 'Charlie', 'Alex', 'Peter', 'Zoe', 'Jim' }, school:roster())
+  end)
+
+  it('grade is empty if no students in the roster', function()
+    local school = School:new()
+    assert.are.same({}, school:grade(1))
+  end)
+
+  it('grade is empty if no students in that grade', function()
+    local school = School:new()
+    school:add('Peter', 2)
+    school:add('Zoe', 2)
+    school:add('Alex', 2)
+    school:add('Jim', 3)
+    assert.are.same({}, school:grade(1))
+  end)
+
+  it('student not added to same grade more than once', function()
+    local school = School:new()
+    school:add('Blair', 2)
+    school:add('James', 2)
+    school:add('James', 2)
+    school:add('Paul', 2)
+    assert.are.same({ 'Blair', 'James', 'Paul' }, school:grade(2))
+  end)
+
+  it('student not added to multiple grades', function()
+    local school = School:new()
+    school:add('Blair', 2)
+    school:add('James', 2)
+    school:add('James', 3)
+    school:add('Paul', 3)
+    assert.are.same({ 'Blair', 'James' }, school:grade(2))
+  end)
+
+  it('student not added to other grade for multiple grades', function()
+    local school = School:new()
+    school:add('Blair', 2)
+    school:add('James', 2)
+    school:add('James', 3)
+    school:add('Paul', 3)
+    assert.are.same({ 'Paul' }, school:grade(3))
+  end)
+
+  it('students are sorted by name in a grade', function()
+    local school = School:new()
+    school:add('Franklin', 5)
+    school:add('Bradley', 5)
+    school:add('Jeff', 1)
+    assert.are.same({ 'Bradley', 'Franklin' }, school:grade(5))
   end)
 end)