This paper proposes a set of algorithms that use Last Planner System® (LPS) metrics, obtained from a software that manage LPS data, and some heuristics to build a Risk Matrix which organizes activities in order of importance. The calculations made by these algorithms are fed by historical project information. The activity importance is determined by the level of impact. This level is defined combining criticality and probability levels that are calculated through the analysis of selected variables: numbers of links between activities, assignment of resources, constraint release history, reasons for noncompletion, percent plan complete (PPC), etc. Identification and prioritization of activities which have a high impact on a project is a useful way to reduce variability, preventing the triggering of chains of delays. Along with this, the mere fact of establishing the most significant activities in front of all participants of planning meetings, generate a psychological effect on all those responsible for tasks, which should align efforts accordingly. This tool is consistent with the LPS philosophy; it takes the team members behavioral history and includes it in the algorithm, producing a warning that indicates that an activity must be followed closely, without assigning responsibility to any team member.