Troubleshooting in a practice situation requires two types of information, namely for reasoning about the problem-cause and for finding an adequate solution ("declarative information") and for manipulating the environment ("procedural information"). It is hypothesized that presenting this information piece-by-piece during practice (i.e., presentation of declarative and procedural information separately) frees up working memory and facilitates learning. Moreover, this effect is augmented when both information types are presented just-in-time (i.e., declarative information "before" practice and procedural information "during" practice). This should yield highest test performance and instructional efficiency, which is defined as higher test performance combined with lower mental effort during practice. Eighty-five students (49 male, 36 female; M = 15.2 years, SD = 0.59) participated in a 2 x 2 factorial experiment with the factors timing of declarative information and timing of procedural information, both "before" or "during" practice. Transfer test scores and transfer efficiency scores support the first hypothesis; the second hypothesis was not supported.