Based on the TEKS an "Applied Music" class can be pretty much whatever an ISD wants it to be as they are exactly the same as for band.
The TEKS below are from: http://ritter.tea.state.tx.us/rules/tac/chapter117/ch117c.html
This is just Music, Level I, they are virtually the same for II, III, and IV. They are the same for band, choir, orchestra and others as listed including Applied Music.
117.310. Music, Level I (One Credit), Adopted 2013.
(a) General requirements. Students may fulfill fine arts and elective requirements for graduation by successfully completing one or more of the following music courses: Band I, Choir I, Orchestra I, Jazz Ensemble I, Jazz Improvisation I, Instrumental Ensemble I, Vocal Ensemble I, World Music Ensemble I, Applied Music I, Mariachi I, Piano I, Guitar I, and Harp I (one credit per course).
(1) The fine arts incorporate the study of dance, music, theatre, and the visual arts to offer unique experiences and empower students to explore realities, relationships, and ideas. These disciplines engage and motivate all students through active learning, critical thinking, and innovative problem solving. The fine arts develop cognitive functioning and increase student academic achievement, higher-order thinking, communication, and collaboration skills, making the fine arts applicable to college readiness, career opportunities, workplace environments, social skills, and everyday life. Students develop aesthetic and cultural awareness through exploration, leading to creative expression. Creativity, encouraged through the study of the fine arts, is essential to nurture and develop the whole child.
(2) Four basic strands--foundations: music literacy; creative expression; historical and cultural relevance; and critical evaluation and response--provide broad, unifying structures for organizing the knowledge and skills students are expected to acquire. The foundation of music literacy is fostered through reading, writing, reproducing, and creating music, thus developing a student's intellect. Through creative expression, students apply their music literacy and the critical-thinking skills of music to sing, play, read, write, and/or move. By experiencing musical periods and styles, students will understand the relevance of music to history, culture, and the world, including the relationship of music to other academic disciplines and the vocational possibilities offered. Through critical listening, students analyze, evaluate, and respond to music, developing criteria for making critical judgments and informed choices.
(3) Statements that contain the word "including" reference content that must be mastered, while those containing the phrase "such as" are intended as possible illustrative examples.
(c) Knowledge and skills.
(1) Foundations: music literacy. The student describes and analyzes music and musical sounds. The student develops organizational skills, engages in problem solving, and explores the properties and capabilities of various musical idioms. The student is expected to:
(A) experience and explore exemplary musical examples using technology and available live performances;
(B) identify and describe melodic and harmonic parts when listening to and performing music using a melodic reading system such as solfège, numbers, letter names, note names, or scale degrees;
(C) define concepts of music notation, intervals, and chord structure using appropriate terminology;
(D) define concepts of rhythm and meter using appropriate terminology and counting system;
(E) explore elements of music such as rhythm, meter, melody, harmony, key, expression markings, texture, form, dynamics, and timbre through literature selected for performance; and
(F) apply health and wellness concepts related to music practice such as body mechanics, hearing protection, vocal health, hydration, and appropriate hygienic practices.
(2) Foundations: music literacy. The student reads and writes music notation using an appropriate notation system. The student is expected to:
(A) read and notate music that incorporates rhythmic patterns in simple, compound, and asymmetric meters; and
(B) interpret music symbols and expressive terms referring to dynamics, tempo, and articulation.
(3) Creative expression. The student demonstrates musical artistry by singing or playing an instrument individually and in groups. The student performs music in a variety of genres at an appropriate level of difficulty. The student performs from notation and by memory as appropriate. The student develops cognitive and psychomotor skills. The student is expected to:
(A) demonstrate mature, characteristic sound appropriate for the genre;
(B) demonstrate psychomotor and kinesthetic skills such as appropriate posture, breathing, text, diction, articulation, vibrato, bowings, fingerings, phrasing, independent manual dexterities, and percussion techniques;
(C) demonstrate rhythmic accuracy using appropriate tempo;
(D) demonstrate observance of key signature and modalities;
(E) demonstrate correct intonation, appropriate phrasing, and appropriate dynamics; and
(F) create and notate or record original musical phrases.
(4) Creative expression. The student sight reads, individually and in groups, by singing or playing an instrument. The student reads from notation at an appropriate level of difficulty in a variety of styles. The student is expected to:
(A) demonstrate mature, characteristic sound appropriate for the genre while sight reading;
(B) demonstrate psychomotor and kinesthetic skills such as use of appropriate posture, breathing, text, diction, articulation, vibrato, bowings, fingerings, phrasing, independent manual dexterities, and percussion techniques while sight reading;
(C) demonstrate rhythmic accuracy while sight reading using a counting system within an appropriate tempo;
(D) demonstrate observance of key signature and modalities while sight reading;
(E) demonstrate use of a melodic reading system such as solfège, numbers, letter names, note names, or scale degrees while sight reading; and
(F) demonstrate correct intonation, appropriate phrasing, and appropriate dynamics while sight reading.
(5) Historical and cultural relevance. The student relates music to history, culture, and the world. The student is expected to:
(A) compare and contrast music by genre, style, culture, and historical period;
(B) identify music-related vocations and avocations;
(C) identify and describe the uses of music in societies and cultures;
(D) identify and explore the relationship between music and other academic disciplines;
(E) identify and explore the impact of technologies, ethical issues, and economic factors on music, performers, and performances; and
(F) identify and explore tools for college and career preparation such as social media applications, repertoire lists, auditions, and interview techniques.
(6) Critical evaluation and response. The student listens to, responds to, and evaluates music and musical performance in both formal and informal settings. The student is expected to:
(A) practice informed concert etiquette as a performer and as an audience member during live and recorded performances in a variety of settings;
(B) design and apply criteria for making informed judgments regarding the quality and effectiveness of musical performances;
(C) develop processes for self-evaluation and select tools for personal artistic improvement; and
(D) evaluate musical performances by comparing them to exemplary models.
Source: The provisions of this §117.310 adopted to be effective July 28, 2013, 38 TexReg 4575.