Although feedback is recognized as one of the most relevant factors to improve learning, its effectivity is highly dependent on the specific setting. In particular, feedback in elementary school students has not been thoroughly studied. Within this scope, studying the effectiveness of different degrees and types of feedback for primary school students becomes relevant. The present study looks at two types of feedback designed for problem-solving in primary school: Knowledge of Results and Elaborated Feedback. A series of interactive problems was designed for tablets to cover a range of topics for fifth-grade mathematics. Through a quasi-experimental design, one group of students (n = 31) was provided with Elaborated Feedback, while another group (n = 33) was provided with Knowledge of Results. Feedback was given to the students as they worked on the interactive problems over 6 sessions. The effectiveness of both types of feedback was then measured using a pre- and post-test. Although Elaborated Feedback helped the students achieve better results during the sessions, the Knowledge of Results group scored higher on the post-test. The results add to the growing debate on the supposed benefits of providing increasing levels of information or guidance, in an area that shows scarce and contradicting evidence.