There is a need for research on the effect of different types of model progressions and learner age on learning and engagement in inquiry-based science settings. This study builds on the Scientific Discovery as Dual Search model to introduce less specific implicit model progression and compares them to the traditional explicit model progression. The data come from Finnish 8-, 10-, and 12-year-olds collaboratively using two different configurations of an inquiry-based learning environment about balance. Balance scale tasks were used to assess learning. Students also rated their situation-specific engagement. Both types of model progressions were beneficial for learning but there was no difference in the normalized change scores between them. The 12-year-olds had a higher normalized change score than the 8-year-olds. There were no differences in situation-specific engagement between the two types of model progression. These results suggest that implicit model progression offers a way to provide less specific guidance and a more open learning environment for primary-aged learners compared to the more specific explicit model progression.