## ARRANGING ADDENDS—TARGET SUM PUZZLES

Grades: 3‒5

Students use logical reasoning skills to arrange circles so that the numbers they enclose equal a given target sum. Students must consider if and how the circles should overlap, so that some numbers appear in up to three circles simultaneously. Sketchpad generates random challenges for the students, or they can create their own problems to share.

OBJECTIVES
• Given a collection of possible addends, students will select those numbers whose sum matches a given target value.
• Students will use logical reasoning to arrange sets of addends so that the numbers satisfy several conditions simultaneously.

COMMON CORE CONNECTIONS
Mathematical Practices

(1) Make sense of problems and persevere in solving them; (2) Reason abstractly and quantitatively; (3) Construct viable arguments and critique the reasoning of others; (5) Use appropriate tools strategically; (7) Look for and make use of structure.

This activity is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License: http://creativecommons.org/licenses/by-nc-sa/3.0/. If you adapt and/or share this activity, you must attribute it to "KCP Technologies, a McGraw-Hill Education Company." You may distribute it only non-commercially under the same or similar license.

This material is based upon work supported by the National Science Foundation under KCP Technologies Award ID 0918733, with grant period September 1, 2009 through August 31, 2013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
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