diff --git a/src/snake_game/constants.py b/src/snake_game/constants.py
index 79ab1f2..270d76a 100644
--- a/src/snake_game/constants.py
+++ b/src/snake_game/constants.py
@@ -117,8 +117,14 @@ SCOREBOARD_FONT: Final[tuple[str, int, str]] = ("Arial", 24, "normal")
 ## @brief The head touches the tail when it is closer to a segment than this, in pixels.
 TAIL_COLLISION_DISTANCE: Final[int] = 10
 
-## @brief Text shown when the game is over.
-GAME_OVER_TEXT: Final[str] = "GAME OVER"
+## @brief Text in front of the high score on the scoreboard.
+#
+#  The scoreboard writes `Score: <score> High Score: <high_score>`: the score
+#  label, the score, a space, this label and the high score.
+HIGH_SCORE_LABEL: Final[str] = "High Score: "
 
-## @brief Where the game-over text is written: the centre of the screen.
-GAME_OVER_POSITION: Final[tuple[int, int]] = (0, 0)
+## @brief Where a segment of the old snake is sent when the snake is reset.
+#
+#  The place is far outside the 600 by 600 screen, so the old segments are out
+#  of sight, as the day-24 lecture does it.
+SEGMENT_PARKING_POSITION: Final[tuple[int, int]] = (1000, 1000)
diff --git a/tests/test_constants.py b/tests/test_constants.py
index b2d4315..d785adc 100644
--- a/tests/test_constants.py
+++ b/tests/test_constants.py
@@ -1,163 +1,171 @@
-"""Tests of the constants that the day-20, day-21 and day-24 lectures fix."""
-
-from snake_game import constants
-
-HALF_WIDTH = constants.SCREEN_WIDTH / 2
-HALF_HEIGHT = constants.SCREEN_HEIGHT / 2
-
-
-def test_screen_size_matches_lecture() -> None:
-    assert (constants.SCREEN_WIDTH, constants.SCREEN_HEIGHT) == (600, 600)
-
-
-def test_screen_is_black_and_titled_as_in_the_lecture() -> None:
-    assert constants.SCREEN_BACKGROUND_COLOR == "black"
-    assert constants.SCREEN_TITLE == "My Snake Game"
-
-
-def test_body_segments_are_light_green_squares() -> None:
-    assert constants.SEGMENT_SHAPE == "square"
-    assert constants.BODY_COLOR == "light green"
-
-
-def test_segment_color_no_longer_exists() -> None:
-    assert not hasattr(constants, "SEGMENT_COLOR")
-
-
-def test_head_is_dark_green_and_differs_from_the_body() -> None:
-    assert constants.HEAD_COLOR == "dark green"
-    assert constants.HEAD_COLOR != constants.BODY_COLOR
-
-
-def test_head_shape_has_a_name_that_is_not_a_built_in_shape() -> None:
-    assert constants.HEAD_SHAPE == "snake_head"
-    assert constants.HEAD_SHAPE != constants.SEGMENT_SHAPE
-
-
-def test_head_is_the_20_by_20_square() -> None:
-    assert constants.HEAD_OUTLINE == ((-10, -10), (-10, 10), (10, 10), (10, -10))
-    xs = {x for x, _ in constants.HEAD_OUTLINE}
-    ys = {y for _, y in constants.HEAD_OUTLINE}
-    assert max(xs) - min(xs) == max(ys) - min(ys) == 20
-
-
-def test_mouth_lies_on_the_front_edge_and_inside_the_head() -> None:
-    front = max(y for _, y in constants.HEAD_OUTLINE)
-    half = max(x for x, _ in constants.HEAD_OUTLINE)
-
-    assert constants.MOUTH_OUTLINE == ((-6, 10), (0, 2), (6, 10))
-    assert any(y == front for _, y in constants.MOUTH_OUTLINE)
-    assert all(
-        abs(x) <= half and -half <= y <= front for x, y in constants.MOUTH_OUTLINE
-    )
-
-
-def test_mouth_is_the_colour_of_the_background() -> None:
-    assert constants.MOUTH_COLOR == constants.SCREEN_BACKGROUND_COLOR
-
-
-def test_snake_starts_with_three_segments_at_the_lecture_positions() -> None:
-    assert constants.STARTING_POSITIONS == ((0, 0), (-20, 0), (-40, 0))
-
-
-def test_starting_positions_are_distinct_on_one_row() -> None:
-    positions = constants.STARTING_POSITIONS
-
-    assert len(set(positions)) == len(positions)
-    assert len({y for _, y in positions}) == 1
-
-
-def test_starting_positions_run_from_head_to_tail_leftwards() -> None:
-    x_values = [x for x, _ in constants.STARTING_POSITIONS]
-
-    assert x_values == sorted(x_values, reverse=True)
-
-
-def test_starting_positions_are_one_move_distance_apart() -> None:
-    x_values = [x for x, _ in constants.STARTING_POSITIONS]
-    gaps = {left - right for left, right in zip(x_values, x_values[1:], strict=False)}
-
-    assert gaps == {constants.MOVE_DISTANCE}
-
-
-def test_starting_positions_are_inside_the_screen() -> None:
-    assert all(
-        abs(x) < HALF_WIDTH and abs(y) < HALF_HEIGHT
-        for x, y in constants.STARTING_POSITIONS
-    )
-
-
-def test_move_distance_is_twenty_pixels() -> None:
-    assert constants.MOVE_DISTANCE == 20
-
-
-def test_directions_match_the_lecture_headings() -> None:
-    assert constants.UP == 90
-    assert constants.DOWN == 270
-    assert constants.LEFT == 180
-    assert constants.RIGHT == 0
-
-
-def test_four_directions_are_distinct() -> None:
-    directions = (constants.UP, constants.DOWN, constants.LEFT, constants.RIGHT)
-
-    assert len(set(directions)) == len(directions)
-
-
-def test_opposite_directions_differ_by_half_a_turn() -> None:
-    assert (constants.UP - constants.DOWN) % 360 == 180
-    assert (constants.LEFT - constants.RIGHT) % 360 == 180
-
-
-def test_refresh_delay_is_a_tenth_of_a_second() -> None:
-    assert constants.REFRESH_DELAY_SECONDS == 0.1
-
-
-def test_food_is_a_small_blue_circle_without_animation() -> None:
-    assert constants.FOOD_SHAPE == "circle"
-    assert constants.FOOD_SIZE == 0.5
-    assert constants.FOOD_COLOR == "blue"
-    assert constants.FOOD_SPEED == "fastest"
-
-
-def test_wall_is_inside_the_screen() -> None:
-    assert 0 < constants.WALL_LIMIT < HALF_WIDTH
-    assert constants.WALL_LIMIT < HALF_HEIGHT
-
-
-def test_wall_is_280_pixels_from_the_centre() -> None:
-    assert constants.WALL_LIMIT == 280
-
-
-def test_food_is_eaten_closer_than_15_pixels_which_is_less_than_a_move() -> None:
-    assert constants.FOOD_COLLISION_DISTANCE == 15
-    assert constants.FOOD_COLLISION_DISTANCE < constants.MOVE_DISTANCE
-
-
-def test_scoreboard_is_white_text_at_the_top_centre_inside_the_screen() -> None:
-    x, y = constants.SCOREBOARD_POSITION
-
-    assert constants.SCOREBOARD_COLOR == "white"
-    assert constants.SCOREBOARD_ALIGNMENT == "center"
-    assert (x, y) == (0, 270)
-    assert abs(x) < HALF_WIDTH
-    assert 0 < y < HALF_HEIGHT
-
-
-def test_scoreboard_text_is_score_label_and_arial_24() -> None:
-    assert constants.SCORE_LABEL == "Score: "
-    assert constants.SCOREBOARD_FONT == ("Arial", 24, "normal")
-
-
-def test_tail_is_touched_closer_than_10_pixels_which_is_less_than_a_move() -> None:
-    assert constants.TAIL_COLLISION_DISTANCE == 10
-    assert 0 < constants.TAIL_COLLISION_DISTANCE < constants.MOVE_DISTANCE
-
-
-def test_game_over_text_is_written_at_the_centre_inside_the_wall() -> None:
-    x, y = constants.GAME_OVER_POSITION
-
-    assert constants.GAME_OVER_TEXT == "GAME OVER"
-    assert (x, y) == (0, 0)
-    assert abs(x) < constants.WALL_LIMIT
-    assert abs(y) < constants.WALL_LIMIT
+"""Tests of the constants that the day-20, day-21 and day-24 lectures fix."""
+
+from snake_game import constants
+
+HALF_WIDTH = constants.SCREEN_WIDTH / 2
+HALF_HEIGHT = constants.SCREEN_HEIGHT / 2
+
+
+def test_screen_size_matches_lecture() -> None:
+    assert (constants.SCREEN_WIDTH, constants.SCREEN_HEIGHT) == (600, 600)
+
+
+def test_screen_is_black_and_titled_as_in_the_lecture() -> None:
+    assert constants.SCREEN_BACKGROUND_COLOR == "black"
+    assert constants.SCREEN_TITLE == "My Snake Game"
+
+
+def test_body_segments_are_light_green_squares() -> None:
+    assert constants.SEGMENT_SHAPE == "square"
+    assert constants.BODY_COLOR == "light green"
+
+
+def test_segment_color_no_longer_exists() -> None:
+    assert not hasattr(constants, "SEGMENT_COLOR")
+
+
+def test_head_is_dark_green_and_differs_from_the_body() -> None:
+    assert constants.HEAD_COLOR == "dark green"
+    assert constants.HEAD_COLOR != constants.BODY_COLOR
+
+
+def test_head_shape_has_a_name_that_is_not_a_built_in_shape() -> None:
+    assert constants.HEAD_SHAPE == "snake_head"
+    assert constants.HEAD_SHAPE != constants.SEGMENT_SHAPE
+
+
+def test_head_is_the_20_by_20_square() -> None:
+    assert constants.HEAD_OUTLINE == ((-10, -10), (-10, 10), (10, 10), (10, -10))
+    xs = {x for x, _ in constants.HEAD_OUTLINE}
+    ys = {y for _, y in constants.HEAD_OUTLINE}
+    assert max(xs) - min(xs) == max(ys) - min(ys) == 20
+
+
+def test_mouth_lies_on_the_front_edge_and_inside_the_head() -> None:
+    front = max(y for _, y in constants.HEAD_OUTLINE)
+    half = max(x for x, _ in constants.HEAD_OUTLINE)
+
+    assert constants.MOUTH_OUTLINE == ((-6, 10), (0, 2), (6, 10))
+    assert any(y == front for _, y in constants.MOUTH_OUTLINE)
+    assert all(
+        abs(x) <= half and -half <= y <= front for x, y in constants.MOUTH_OUTLINE
+    )
+
+
+def test_mouth_is_the_colour_of_the_background() -> None:
+    assert constants.MOUTH_COLOR == constants.SCREEN_BACKGROUND_COLOR
+
+
+def test_snake_starts_with_three_segments_at_the_lecture_positions() -> None:
+    assert constants.STARTING_POSITIONS == ((0, 0), (-20, 0), (-40, 0))
+
+
+def test_starting_positions_are_distinct_on_one_row() -> None:
+    positions = constants.STARTING_POSITIONS
+
+    assert len(set(positions)) == len(positions)
+    assert len({y for _, y in positions}) == 1
+
+
+def test_starting_positions_run_from_head_to_tail_leftwards() -> None:
+    x_values = [x for x, _ in constants.STARTING_POSITIONS]
+
+    assert x_values == sorted(x_values, reverse=True)
+
+
+def test_starting_positions_are_one_move_distance_apart() -> None:
+    x_values = [x for x, _ in constants.STARTING_POSITIONS]
+    gaps = {left - right for left, right in zip(x_values, x_values[1:], strict=False)}
+
+    assert gaps == {constants.MOVE_DISTANCE}
+
+
+def test_starting_positions_are_inside_the_screen() -> None:
+    assert all(
+        abs(x) < HALF_WIDTH and abs(y) < HALF_HEIGHT
+        for x, y in constants.STARTING_POSITIONS
+    )
+
+
+def test_move_distance_is_twenty_pixels() -> None:
+    assert constants.MOVE_DISTANCE == 20
+
+
+def test_directions_match_the_lecture_headings() -> None:
+    assert constants.UP == 90
+    assert constants.DOWN == 270
+    assert constants.LEFT == 180
+    assert constants.RIGHT == 0
+
+
+def test_four_directions_are_distinct() -> None:
+    directions = (constants.UP, constants.DOWN, constants.LEFT, constants.RIGHT)
+
+    assert len(set(directions)) == len(directions)
+
+
+def test_opposite_directions_differ_by_half_a_turn() -> None:
+    assert (constants.UP - constants.DOWN) % 360 == 180
+    assert (constants.LEFT - constants.RIGHT) % 360 == 180
+
+
+def test_refresh_delay_is_a_tenth_of_a_second() -> None:
+    assert constants.REFRESH_DELAY_SECONDS == 0.1
+
+
+def test_food_is_a_small_blue_circle_without_animation() -> None:
+    assert constants.FOOD_SHAPE == "circle"
+    assert constants.FOOD_SIZE == 0.5
+    assert constants.FOOD_COLOR == "blue"
+    assert constants.FOOD_SPEED == "fastest"
+
+
+def test_wall_is_inside_the_screen() -> None:
+    assert 0 < constants.WALL_LIMIT < HALF_WIDTH
+    assert constants.WALL_LIMIT < HALF_HEIGHT
+
+
+def test_wall_is_280_pixels_from_the_centre() -> None:
+    assert constants.WALL_LIMIT == 280
+
+
+def test_food_is_eaten_closer_than_15_pixels_which_is_less_than_a_move() -> None:
+    assert constants.FOOD_COLLISION_DISTANCE == 15
+    assert constants.FOOD_COLLISION_DISTANCE < constants.MOVE_DISTANCE
+
+
+def test_scoreboard_is_white_text_at_the_top_centre_inside_the_screen() -> None:
+    x, y = constants.SCOREBOARD_POSITION
+
+    assert constants.SCOREBOARD_COLOR == "white"
+    assert constants.SCOREBOARD_ALIGNMENT == "center"
+    assert (x, y) == (0, 270)
+    assert abs(x) < HALF_WIDTH
+    assert 0 < y < HALF_HEIGHT
+
+
+def test_scoreboard_text_is_score_label_and_arial_24() -> None:
+    assert constants.SCORE_LABEL == "Score: "
+    assert constants.SCOREBOARD_FONT == ("Arial", 24, "normal")
+
+
+def test_tail_is_touched_closer_than_10_pixels_which_is_less_than_a_move() -> None:
+    assert constants.TAIL_COLLISION_DISTANCE == 10
+    assert 0 < constants.TAIL_COLLISION_DISTANCE < constants.MOVE_DISTANCE
+
+
+def test_game_over_constants_no_longer_exist() -> None:
+    assert not hasattr(constants, "GAME_OVER_TEXT")
+    assert not hasattr(constants, "GAME_OVER_POSITION")
+
+
+def test_high_score_label_follows_the_score_label_as_in_the_lecture() -> None:
+    assert constants.HIGH_SCORE_LABEL == "High Score: "
+    assert constants.HIGH_SCORE_LABEL != constants.SCORE_LABEL
+
+
+def test_old_segments_are_parked_outside_the_screen() -> None:
+    x, y = constants.SEGMENT_PARKING_POSITION
+
+    assert abs(x) > HALF_WIDTH
+    assert abs(y) > HALF_HEIGHT