MP6: Attend to precision.
Precision involves using appropriate vocabulary, measurement units, graph labels, and symbols. It also includes adjusting answers to be appropriate for the context of the problem. For example, if the answer to an area or volume question has more nonzero digits than the given information, digits that don't make sense should be rounded. In summary, students need to "pay attention to details" when writing or showing answers to problems. For my students, I extend this to include neatness in written work.
MP7: Look for and make use of structure.
Proficient students can discern patterns and structure in problems. In both geometric and numeric problems, students should be encouraged to break apart or combine parts as they look for patterns. It may also be helpful to sort or rearrange information. An easier summary statement for this standard is to "break apart problems."
MP8: Look for and express regularity in repeated reasoning.
With elementary students, I call this the "look for shortcuts" standard. Students should notice similarities between problems and look for general methods and shortcuts. In the past, some math teachers have expected students to show every step in calculations or solving equations. But to be proficient in math, it is important to recognize and apply shortcuts. For example, students in Grades 4-8 may be able to solve an equation such as 500 + x = 560 by mentally thinking of the missing addend. Because of the general relationship between subtraction and finding a missing addend, students should be encouraged to solve this mentally rather than writing a step of subtracting 500 from each side. The use of shortcuts should be rewarded, not penalized.
Overall, the goal of the Standards for Mathematical Practice is to help students learn habits and processes for solving problems. By encouraging students to pay attention to details, break apart problems, and look for shortcuts, you will help them become better problem solvers.I have developed a set of 12 posters called "Be a Star" that have checklists and an icon for each practice standard written in language that is easier for elementary students to understand. You can find these on the following site:
http://www.mathpaths.com/practice.html