The Texas Education Code is part of the Texas statutes and can be found online. The link below will take you to Texas Constitution and Statutes Online. The drop down menu for "Code" will allow you to select "Education Code," followed by the various titles, chapters, and sections.
The Texas Administrative Code, Title 19 Education, deals with all the public education administrative regulations in Texas for primary, secondary, and higher education. The link below takes you to this.
Within the Texas Administrative Code you will find the specific Texas Essential Knowledge and Skills (TEKS), which detail the specific objectives and goals to be taught for each class and subject. The link below will take you to the main page, with the TEKS beginning at Chapter 110.