diff --git a/tests/backup_restore_test.php b/tests/backup_restore_test.php
new file mode 100644
index 00000000..c27af3cf
--- /dev/null
+++ b/tests/backup_restore_test.php
@@ -0,0 +1,195 @@
+<?php
+// This file is part of Moodle - https://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <https://www.gnu.org/licenses/>.
+
+/**
+ * Unit tests for backup and restore.
+ *
+ * @package    qtype_formulas
+ * @copyright  2025 Philipp Imhof
+ * @license    https://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace qtype_formulas;
+
+use backup;
+use backup_controller;
+use context_course;
+use core_question_generator;
+use qtype_formulas;
+use qtype_formulas_question;
+use restore_controller;
+use test_question_maker;
+
+defined('MOODLE_INTERNAL') || die();
+
+global $CFG;
+require_once($CFG->dirroot . '/backup/util/includes/backup_includes.php');
+require_once($CFG->dirroot . '/backup/util/includes/restore_includes.php');
+require_once($CFG->dirroot . '/mod/quiz/locallib.php');
+require_once($CFG->dirroot . '/mod/quiz/tests/quiz_question_helper_test_trait.php');
+require_once($CFG->dirroot . '/question/engine/tests/helpers.php');
+require_once($CFG->dirroot . '/question/type/formulas/questiontype.php');
+require_once($CFG->dirroot . '/question/type/formulas/tests/helper.php');
+
+/**
+ * Unit tests for backup and restore.
+ *
+ * @copyright  2025 Philipp Imhof
+ * @license    https://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ *
+ * @covers     \restore_qtype_formulas_plugin
+ * @covers     \backup_qtype_formulas_plugin
+ * @covers     \qtype_formulas
+ * @covers     \qtype_formulas_question
+ * @covers     \qtype_formulas_part
+ */
+final class backup_restore_test extends \advanced_testcase {
+    use \quiz_question_helper_test_trait;
+
+    /**
+     * Create a question object of a certain type, as defined in the helper.php file.
+     *
+     * @return qtype_formulas_question
+     */
+    protected function get_test_formulas_question($which = null) {
+        return test_question_maker::make_question('formulas', $which);
+    }
+
+    /**
+     * Data provider.
+     *
+     * @return array
+     */
+    public static function provide_question_names(): array {
+        return [
+            ['testsinglenum'],
+            ['testsinglenumunit'],
+            ['testsinglenumunitsep'],
+            ['testtwonums'],
+            ['testthreeparts'],
+            ['test4'],
+            ['testmethodsinparts'],
+            ['testalgebraic'],
+        ];
+    }
+
+    /**
+     * Backup and restore a question and check whether the data matches.
+     *
+     * @param string $questionname name of the test question (e. g. testsinglenum)
+     * @dataProvider provide_question_names
+     */
+    public function test_backup_and_restore(string $questionname): void {
+        global $USER, $DB;
+
+        // Login as admin user.
+        $this->resetAfterTest(true);
+        $this->setAdminUser();
+
+        // Create a course and a quiz with a Formulas question.
+        $generator = $this->getDataGenerator();
+        /** @var \core_question_generator $questiongenerator */
+        $questiongenerator = $this->getDataGenerator()->get_plugin_generator('core_question');
+        $course = $generator->create_course();
+        $context = context_course::instance($course->id);
+        $cat = $questiongenerator->create_question_category(['contextid' => $context->id]);
+        $question = $questiongenerator->create_question('formulas', $questionname, ['category' => $cat->id]);
+        quiz_add_quiz_question($question->id, $this->create_test_quiz($course));
+
+        // Backup course. By using MODE_IMPORT, we avoid the backup being zipped.
+        $bc = new backup_controller(
+            backup::TYPE_1COURSE, $course->id, backup::FORMAT_MOODLE, backup::INTERACTIVE_NO, backup::MODE_IMPORT, $USER->id
+        );
+        $backupid = $bc->get_backupid();
+        $bc->execute_plan();
+        $bc->destroy();
+
+        // Delete the current course to make sure there is no data.
+        delete_course($course, false);
+
+        // Create a new course and restore the backup.
+        $newcourse = $generator->create_course();
+        $context = context_course::instance($newcourse->id);
+        $rc = new restore_controller(
+            $backupid, $newcourse->id, backup::INTERACTIVE_NO, backup::MODE_IMPORT, $USER->id, backup::TARGET_NEW_COURSE
+        );
+        $rc->execute_precheck();
+        $rc->execute_plan();
+        $rc->destroy();
+
+        // Fetch the quiz and question ID.
+        $modules = get_fast_modinfo($newcourse->id)->get_instances_of('quiz');
+        $quiz = reset($modules);
+        $structure = \mod_quiz\question\bank\qbank_helper::get_question_structure($quiz->instance, $quiz->context);
+        $question = reset($structure);
+
+        // Fetch the question and its additional data (random vars, global vars, parts) from the DB.
+        $questionrecord = $DB->get_record('question', ['id' => $question->questionid], '*', MUST_EXIST);
+        $qtype = new qtype_formulas();
+        $qtype->get_question_options($questionrecord);
+
+        // Fetch the reference data for the given question.
+        $referencedata = test_question_maker::make_question('formulas', $questionname);
+
+        // First, we check the data for the main question, i. e. basic fields plus custom data for the
+        // Formulas question like varsrandom or varsglobal.
+        $basicfields = [
+            'name',
+            'questiontext',
+            'questiontextformat',
+            'generalfeedback',
+            'generalfeedbackformat',
+            'defaultmark',
+            'penalty',
+        ];
+        $questionfields = $basicfields + array_slice($qtype->extra_question_fields(), 1);
+        foreach ($questionfields as $field) {
+            self::assertEquals($referencedata->$field, $questionrecord->$field, $field);
+        }
+
+        // Next, we check the fields for each part.
+        $partfields = qtype_formulas::PART_BASIC_FIELDS + ['subqtext', 'subqtextformat', 'feedback', 'feedbackformat'];
+        foreach ($partfields as $field) {
+            foreach ($questionrecord->options->answers as $i => $part) {
+                self::assertEquals($referencedata->parts[$i]->$field, $part->$field, $field);
+            }
+        }
+
+        // Finally, we check the combined feedback fields for the parts and the main question.
+        $feedbackfields = ['correctfeedback', 'partiallycorrectfeedback', 'incorrectfeedback'];
+        foreach ($feedbackfields as $field) {
+            self::assertEquals($referencedata->$field, $questionrecord->options->$field, $field);
+            $fieldformat = $field . 'format';
+            self::assertEquals($referencedata->$fieldformat, $questionrecord->options->$fieldformat, $fieldformat);
+            $origfield = $field;
+            foreach ($questionrecord->options->answers as $i => $part) {
+                $field = 'part' . str_replace('feedback', 'fb', $origfield);
+                self::assertEquals($referencedata->parts[$i]->$field, $part->$field, $field);
+                $fieldformat = $field . 'format';
+                self::assertEquals($referencedata->parts[$i]->$fieldformat, $part->$fieldformat);
+            }
+        }
+
+        // Finally, compare the hints.
+        $hintfields = ['hint', 'hintformat', 'shownumcorrect', 'clearwrong'];
+        $keys = array_keys($questionrecord->hints);
+        foreach ($referencedata->hints as $i => $hint) {
+            foreach ($hintfields as $field) {
+                self::assertEquals($hint->$field, $questionrecord->hints[$keys[$i]]->$field, $field);
+            }
+        }
+    }
+}
diff --git a/tests/behat/export.feature b/tests/behat/export.feature
index 0dfd6f74..1bdc0839 100644
--- a/tests/behat/export.feature
+++ b/tests/behat/export.feature
@@ -27,7 +27,7 @@ Feature: Test exporting Formulas questions
     When I am on the "Course 1" "core_question > course question export" page
     And I set the field "id_format_xml" to "1"
     And I press "Export questions to file"
-    Then following "click here" should download between "6100" and "6300" bytes
+    Then following "click here" should download between "6250" and "6500" bytes
     # If the download step is the last in the scenario then we can sometimes run
     # into the situation where the download page causes a http redirect but behat
     # has already conducted its reset (generating an error). By putting a logout
diff --git a/tests/behat/mobile.feature b/tests/behat/mobile.feature
index d0ff9e40..6c70bcdb 100644
--- a/tests/behat/mobile.feature
+++ b/tests/behat/mobile.feature
@@ -98,7 +98,7 @@ Feature: Mobile compatibility
     And I press "Submit" in the app
     And I press "Submit all and finish" in the app
     And I press "Submit" near "Once you submit" in the app
-    Then I should find "Your answer is correct." in the app
+    Then I should find "Correct answer, well done." in the app
 
   Scenario: Try to answer a question with one answer + one unit field
     When I press "Quiz 4" in the app
diff --git a/tests/behat/quiz.feature b/tests/behat/quiz.feature
index 6c4affe2..3594e5ef 100644
--- a/tests/behat/quiz.feature
+++ b/tests/behat/quiz.feature
@@ -99,7 +99,7 @@ Feature: Usage in quiz
     And I press "Finish attempt"
     And I press "Submit all and finish"
     # And I confirm the quiz submission in the modal dialog
-    Then I should see "Your answer is correct."
+    Then I should see "Correct answer, well done."
 
   Scenario: Try to answer a question with one answer + one unit field
     When I follow "Quiz 4"
diff --git a/tests/helper.php b/tests/helper.php
index 184cbf40..15b52ff5 100644
--- a/tests/helper.php
+++ b/tests/helper.php
@@ -142,7 +142,7 @@ public static function make_formulas_question_testalgebraic() {
         $q->name = 'test-algebraic';
         $q->questiontext = '<p>This is a minimal question. The answer is "5*x^2".</p>';
 
-        $q->penalty = 0.3;
+        $q->penalty = 0.2;
         $q->textfragments = [0 => '<p>This is a minimal question. The answer is "5*x^2".</p>',
                                   1 => ''];
         $q->numparts = 1;
@@ -199,7 +199,7 @@ public function get_formulas_question_form_data_testalgebraic() {
         $form->defaultmark = 2;
         $form->penalty = 0.2;
         $form->varsrandom = '';
-        $form->varsglobal = '';
+        $form->varsglobal = 'a=5;';
         $form->answernumbering = 'abc';
         $form->globalunitpenalty = 1;
         $form->globalruleid = 1;
@@ -300,6 +300,12 @@ public function get_formulas_question_form_data_testsinglenum(): stdClass {
         ];
         $form->incorrectfeedback = ['text' => test_question_maker::STANDARD_OVERALL_INCORRECT_FEEDBACK, 'format' => FORMAT_HTML];
         $form->shownumcorrect = '1';
+        $form->hint = [
+            ['text' => 'Hint 1.', 'format' => FORMAT_HTML],
+            ['text' => 'Hint 2.', 'format' => FORMAT_HTML],
+        ];
+        $form->hintclearwrong = [0, 1];
+        $form->hintshownumcorrect = [1, 1];
         return $form;
     }
 
@@ -447,13 +453,13 @@ public function get_formulas_question_form_data_testsinglenumunit() {
             ['text' => '', 'format' => FORMAT_HTML],
         ];
         $form->partcorrectfb = [
-            ['text' => 'Your answer is correct.', 'format' => FORMAT_HTML],
+            ['text' => '<p>Correct answer, well done.</p>', 'format' => FORMAT_HTML],
         ];
         $form->partpartiallycorrectfb = [
-            ['text' => 'Your answer is partially correct.', 'format' => FORMAT_HTML],
+            ['text' => '<p>Your answer is partially correct.</p>', 'format' => FORMAT_HTML],
         ];
         $form->partincorrectfb = [
-            ['text' => 'Your answer is incorrect.', 'format' => FORMAT_HTML],
+            ['text' => '<p>Incorrect answer.</p>', 'format' => FORMAT_HTML],
         ];
         $form->questiontext = ['text' => '<p>One part, one number plus unit, answer is 5 m/s</p>',
                 'format' => FORMAT_HTML];
@@ -465,10 +471,13 @@ public function get_formulas_question_form_data_testsinglenumunit() {
         $form->answernumbering = 'abc';
         $form->globalunitpenalty = 1;
         $form->globalruleid = 1;
-        $form->correctfeedback = ['text' => '', 'format' => FORMAT_HTML];
-        $form->partiallycorrectfeedback = ['text' => '', 'format' => FORMAT_HTML];
+        $form->correctfeedback = ['text' => 'Well done!', 'format' => FORMAT_HTML];
+        $form->partiallycorrectfeedback = [
+            'text' => 'Parts, but only parts, of your response are correct.',
+            'format' => FORMAT_HTML,
+        ];
         $form->shownumcorrect = '0';
-        $form->incorrectfeedback = ['text' => '', 'format' => FORMAT_HTML];
+        $form->incorrectfeedback = ['text' => 'That is not right at all.', 'format' => FORMAT_HTML];
         return $form;
     }
 
@@ -582,7 +591,7 @@ public static function make_formulas_question_testsinglenumunitsep(): qtype_form
     public function get_formulas_question_form_data_testsinglenumunitsep() {
         $form = new stdClass();
 
-        $form->name = 'test-singlenumunit';
+        $form->name = 'test-singlenumunitsep';
         $form->noanswers = 1;
         $form->answer = ['5'];
         $form->answernotunique = ['1'];
@@ -622,10 +631,13 @@ public function get_formulas_question_form_data_testsinglenumunitsep() {
         $form->answernumbering = 'abc';
         $form->globalunitpenalty = 1;
         $form->globalruleid = 1;
-        $form->correctfeedback = ['text' => '', 'format' => FORMAT_HTML];
-        $form->partiallycorrectfeedback = ['text' => '', 'format' => FORMAT_HTML];
+        $form->correctfeedback = ['text' => 'Well done!', 'format' => FORMAT_HTML];
+        $form->partiallycorrectfeedback = [
+            'text' => 'Parts, but only parts, of your response are correct.',
+            'format' => FORMAT_HTML,
+        ];
         $form->shownumcorrect = '0';
-        $form->incorrectfeedback = ['text' => '', 'format' => FORMAT_HTML];
+        $form->incorrectfeedback = ['text' => 'That is not right at all.', 'format' => FORMAT_HTML];
         return $form;
     }
 
@@ -719,6 +731,7 @@ public static function make_formulas_question_testtwonums(): qtype_formulas_ques
         $p->placeholder = '';
         $p->answermark = 2;
         $p->answer = '[2, 3]';
+        $p->numbox = 2;
         $p->answernotunique = '1';
         $p->subqtext = '';
         $p->partcorrectfb = 'Your answer is correct.';
@@ -742,7 +755,7 @@ public function get_formulas_question_form_data_testtwonums() {
         $form->answermark = [2];
         $form->answertype = ['0'];
         $form->correctness = ['_relerr < 0.01'];
-        $form->numbox = [1, 1];
+        $form->numbox = [2];
         $form->placeholder = [''];
         $form->vars1 = [''];
         $form->vars2 = [''];
@@ -773,10 +786,13 @@ public function get_formulas_question_form_data_testtwonums() {
         $form->answernumbering = '';
         $form->globalunitpenalty = 1;
         $form->globalruleid = 1;
-        $form->correctfeedback = ['text' => '', 'format' => FORMAT_HTML];
-        $form->partiallycorrectfeedback = ['text' => '', 'format' => FORMAT_HTML];
+        $form->correctfeedback = ['text' => 'Well done!', 'format' => FORMAT_HTML];
+        $form->partiallycorrectfeedback = [
+            'text' => 'Parts, but only parts, of your response are correct.',
+            'format' => FORMAT_HTML,
+        ];
         $form->shownumcorrect = '0';
-        $form->incorrectfeedback = ['text' => '', 'format' => FORMAT_HTML];
+        $form->incorrectfeedback = ['text' => 'That is not right at all.', 'format' => FORMAT_HTML];
         return $form;
     }
 
@@ -891,10 +907,13 @@ public function get_formulas_question_form_data_testthreeparts() {
             ['text' => 'Part 2 incorrect feedback.', 'format' => FORMAT_HTML],
             ['text' => 'Part 3 incorrect feedback.', 'format' => FORMAT_HTML],
         ];
-        $form->correctfeedback = ['text' => '', 'format' => FORMAT_HTML];
-        $form->partiallycorrectfeedback = ['text' => '', 'format' => FORMAT_HTML];
+        $form->correctfeedback = ['text' => 'Well done!', 'format' => FORMAT_HTML];
+        $form->partiallycorrectfeedback = [
+            'text' => 'Parts, but only parts, of your response are correct.',
+            'format' => FORMAT_HTML,
+        ];
         $form->shownumcorrect = '0';
-        $form->incorrectfeedback = ['text' => '', 'format' => FORMAT_HTML];
+        $form->incorrectfeedback = ['text' => 'That is not right at all.', 'format' => FORMAT_HTML];
         $form->numhints = 2;
         $form->hint = [
             ['text' => '', 'format' => FORMAT_HTML],
@@ -918,6 +937,7 @@ public static function make_formulas_question_testmethodsinparts(): qtype_formul
         $q->defaultmark = 8;
         $q->penalty = 0.3; // Non-zero and not the default.
         $q->numparts = 4;
+        $q->generalfeedback = 'This is the general feedback.';
         $q->textfragments = [0 => '<p>This question shows different display methods of the answer and unit box.</p>',
                 1 => '',
                 2 => '',
@@ -992,7 +1012,7 @@ public static function get_formulas_question_data_testmethodsinparts() {
         $qdata->qtype = 'formulas';
         $qdata->name = 'test-methodsinparts';
         $qdata->questiontext = '<p>This question shows different display methods of the answer and unit box.</p>';
-        $qdata->generalfeedback = '';
+        $qdata->generalfeedback = 'This is the general feedback.';
         $qdata->defaultmark = 8;
         $qdata->penalty = 0.3;
 
@@ -1287,11 +1307,11 @@ public function get_formulas_question_form_data_testmethodsinparts() {
         $form->shownumcorrect = '1';
         $form->numhints = 2;
         $form->hint = [
-            ['text' => '', 'format' => FORMAT_HTML],
-            ['text' => '', 'format' => FORMAT_HTML],
+            ['text' => 'Hint 1.', 'format' => FORMAT_HTML],
+            ['text' => 'Hint 2.', 'format' => FORMAT_HTML],
         ];
-        $form->hintclearwrong = ['0', '0'];
-        $form->hintshownumcorrect = ['0', '0'];
+        $form->hintclearwrong = [0, 1];
+        $form->hintshownumcorrect = [1, 1];
         return $form;
     }
 
@@ -1386,6 +1406,7 @@ public static function make_formulas_question_test4(): qtype_formulas_question {
         $q->defaultmark = 8;
         $q->penalty = 0.3; // Non-zero and not the default.
         $q->numparts = 4;
+        $q->generalfeedback = 'This is the general feedback.';
         $q->textfragments = [0 => '<p>This question shows different display methods of the answer and unit box.</p>',
                 1 => '',
                 2 => '',
@@ -1491,27 +1512,30 @@ public function get_formulas_question_form_data_test4() {
             ['text' => '', 'format' => FORMAT_HTML],
         ];
         $form->partcorrectfb = [
-            ['text' => '', 'format' => FORMAT_HTML],
-            ['text' => '', 'format' => FORMAT_HTML],
-            ['text' => '', 'format' => FORMAT_HTML],
-            ['text' => '', 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_CORRECT_FEEDBACK, 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_CORRECT_FEEDBACK, 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_CORRECT_FEEDBACK, 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_CORRECT_FEEDBACK, 'format' => FORMAT_HTML],
         ];
         $form->partpartiallycorrectfb = [
-            ['text' => '', 'format' => FORMAT_HTML],
-            ['text' => '', 'format' => FORMAT_HTML],
-            ['text' => '', 'format' => FORMAT_HTML],
-            ['text' => '', 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_PARTIALLYCORRECT_FEEDBACK, 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_PARTIALLYCORRECT_FEEDBACK, 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_PARTIALLYCORRECT_FEEDBACK, 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_PARTIALLYCORRECT_FEEDBACK, 'format' => FORMAT_HTML],
         ];
         $form->partincorrectfb = [
-            ['text' => '', 'format' => FORMAT_HTML],
-            ['text' => '', 'format' => FORMAT_HTML],
-            ['text' => '', 'format' => FORMAT_HTML],
-            ['text' => '', 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_INCORRECT_FEEDBACK, 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_INCORRECT_FEEDBACK, 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_INCORRECT_FEEDBACK, 'format' => FORMAT_HTML],
+            ['text' => self::DEFAULT_INCORRECT_FEEDBACK, 'format' => FORMAT_HTML],
+        ];
+        $form->correctfeedback = ['text' => 'Well done!', 'format' => FORMAT_HTML];
+        $form->partiallycorrectfeedback = [
+            'text' => 'Parts, but only parts, of your response are correct.',
+            'format' => FORMAT_HTML,
         ];
-        $form->correctfeedback = ['text' => '', 'format' => FORMAT_HTML];
-        $form->partiallycorrectfeedback = ['text' => '', 'format' => FORMAT_HTML];
         $form->shownumcorrect = '0';
-        $form->incorrectfeedback = ['text' => '', 'format' => FORMAT_HTML];
+        $form->incorrectfeedback = ['text' => 'That is not right at all.', 'format' => FORMAT_HTML];
         $form->numhints = 2;
         $form->hint = [
             ['text' => '', 'format' => FORMAT_HTML],