TI-15_Explorer TI-15 Explorer is a calculator designed by Texas Instruments, intended for use in classes from grades 3-5. For younger students, TI recommends the use of the TI-10. For older students, TI recommends the use of the TI-73 Explorer.Features include a 2-line pixel display (as opposed to the 7-segment display of several other calculators), and a quiz-like "problem-solving" mode.scientific capabilities, such as parentheses, fixed decimal, pi, and exponents.