diff --git a/.github/classroom/autograding.json b/.github/classroom/autograding.json
index 8c381f5..568eeff 100644
--- a/.github/classroom/autograding.json
+++ b/.github/classroom/autograding.json
@@ -2,8 +2,8 @@
   "tests": [
     {
       "name": "setup",
-      "setup": "python3 -m pip install -U pip",
-      "run": "python3 -m pip install numpy setuptools pytest pytest-timeout flake8 pep8-naming flake8-docstrings",
+      "setup": "python3 -m venv venv",
+      "run": "venv/bin/python -m pip install numpy pytest pytest-timeout flake8 pep8-naming flake8-docstrings",
       "input": "",
       "output": "",
       "comparison": "included",
@@ -13,7 +13,7 @@
     {
       "name": "package-install",
       "setup": "",
-      "run": "python3 -m pip install -e .",
+      "run": "venv/bin/python -m pip install -e .",
       "input": "",
       "output": "",
       "comparison": "included",
@@ -23,7 +23,7 @@
     {
       "name": "exercise-5-4",
       "setup": "",
-      "run": "python3 -m pytest tests/test_exercise_5_4.py",
+      "run": "venv/bin/python -m pytest tests/test_exercise_5_4.py",
       "input": "",
       "output": "",
       "comparison": "included",
@@ -33,7 +33,7 @@
     {
       "name": "exercise-5-5",
       "setup": "",
-      "run": "python3 -m pytest tests/test_exercise_5_5.py",
+      "run": "venv/bin/python -m pytest tests/test_exercise_5_5.py",
       "input": "",
       "output": "",
       "comparison": "included",
@@ -43,7 +43,7 @@
     {
       "name": "exercise-5-6",
       "setup": "",
-      "run": "python3 -m pytest tests/test_exercise_5_6.py",
+      "run": "venv/bin/python -m pytest tests/test_exercise_5_6.py",
       "input": "",
       "output": "",
       "comparison": "included",
@@ -53,7 +53,7 @@
     {
       "name": "flake8-test",
       "setup": "",
-      "run": "python3 -m flake8 adt_examples/",
+      "run": "venv/bin/python -m flake8 adt_examples/",
       "input": "",
       "output": "",
       "comparison": "included",
diff --git a/.github/workflows/classroom.yml b/.github/workflows/classroom.yml
index 8e05703..3142cbe 100644
--- a/.github/workflows/classroom.yml
+++ b/.github/workflows/classroom.yml
@@ -7,5 +7,5 @@
         name: Autograding
         runs-on: ubuntu-latest
         steps:
-          - uses: actions/checkout@v2
+          - uses: actions/checkout@v4
           - uses: education/autograding@v1
diff --git a/conftest.py b/conftest.py
deleted file mode 100644
index 8b13789..0000000
--- a/conftest.py
+++ /dev/null
@@ -1 +0,0 @@
-
diff --git a/tests/test_exercise_5_6.py b/tests/test_exercise_5_6.py
index c482b23..737fedf 100644
--- a/tests/test_exercise_5_6.py
+++ b/tests/test_exercise_5_6.py
@@ -118,6 +118,17 @@ def test_pointers(idx, iterated, base_data):
     assert np.array_equal([q for q in Q], iterated)
 
 
+@pytest.mark.parametrize("idx, iterated", [
+    (0, [15, 20, 25, 35, 40]),
+    (1, ['n+3', 'n+2', 'n', 'n+4'])
+])
+def test_double_iterate(idx, iterated, base_data):
+    Q = base_data[idx]
+    assert np.array_equal([(q, r) for q in Q for r in Q],
+                          [(q, r) for q in iterated for r in iterated])
+
+
+
 def test_mem_leakage():
     Q = Deque(2)
     Q.append(1)