public override void Start(HumanSubject current_subject = null)
        {
            if (current_subject != null)
            {
                current_subject_obj = current_subject;

                //Get the list of words to use for this test block
                var hal_config = HumanAcceleratedLearningConfiguration.GetInstance();
                source_language_dictionary = hal_config.LanguageDictionaries.Where(x =>
                                                                                   (x.ForeignLanguageName.Equals(ForeignLanguage) &&
                                                                                    x.NativeLanguageName.Equals(NativeLanguage))
                                                                                   ).FirstOrDefault();

                //Get the list of words that this participant has already gotten correct in previous test blocks
                current_subject.MakeSureCorrectlyAnsweredWordListExistsForSubject(ForeignLanguage);
                if (source_language_dictionary != null)
                {
                    var correct_word_list = current_subject.CorrectlyAnsweredWordList[ForeignLanguage];
                    var all_word_pairs    = source_language_dictionary.DictionaryWordPairs.ToList();
                    var ordered_foreign_language_Words = all_word_pairs.Select(x => x.Item1).ToList();

                    //Remove the words from the list of word pairs that have already been answered correctly
                    for (int i = 0; i < correct_word_list.Count; i++)
                    {
                        int index = ordered_foreign_language_Words.IndexOf(correct_word_list[i]);
                        if (index > -1)
                        {
                            ordered_foreign_language_Words.RemoveAt(index);
                            all_word_pairs.RemoveAt(index);
                        }
                    }

                    //Shuffle the remaining words
                    shuffled_word_list     = MathHelperMethods.ShuffleList(all_word_pairs);
                    last_word_display_time = DateTime.MinValue;
                    test_start_time        = DateTime.Now;
                    current_wordpair_index = 0;

                    //Create a file for this test session
                    fid = TestBlock.CreateTestBlockFile(current_subject.UserName);

                    HasPhaseStarted = true;
                }
            }
        }