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CROSS NUMBER PUZZLES—ADDITION AND SUBTRACTION

Grades: K‒4

Students solve a collection of puzzles in which they add, subtract, and use logical reasoning to find missing numbers in a 3 × 3 grid. Through multiple plays of random challenges generated by Sketchpad, students work to improve their strategies and scores. The activity concludes with students identifying the strategies they used to solve the puzzles.

OBJECTIVES 
  • Students will use puzzles to practice addition and subtraction facts.
  • Students will compose and decompose two-digit numbers into tens and units.
  • Students will develop strategies, using logical thinking and their understanding of place value, to recognize which rows or columns of a cross-number puzzle are suitable for immediate solution and which require other rows or columns to be solved first.
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; (6) Attend to precision; (7) Look for and make use of structure; (8) Look for and express regularity in repeated reasoning.

Content Standards

1.OA1, 3, 4, 6, 7, 8; 1.NBT1, 2, 4, 6; 2.OA1, 2; 2.NBT1, 5, 6, 7, 9; 3.A1; 3.NBT2

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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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