In this activity, students will use both math and logic to solve a chemistry themed kakuro puzzle. This puzzle differs slightly from a traditional kakuro by first requiring students to use a periodic table to find the atomic number for each element symbol appearing in the puzzle. Using the atomic numbers as starting clues, students then fill-in the empty squares with numbers 1-9 that sum to the value of the clue, but without reusing any digits. This activity is a fun challenge for students and provides the opportunity to strengthen logic and reasoning skills.
High School and Middle School
This activity will help prepare your students to meet the performance expectations in the following standards:
- Scientific and Engineering Practices:
- Using Mathematics and Computational Thinking
By the end of this activity, students should be able to:
- Determine the atomic number of an element, given the element symbol.
- Follow the rules in order to properly solve a math-based puzzle.
This activity supports students’ understanding of:
- Periodic Table
- Atomic Number
Teacher Preparation: minimal
Lesson: 15-20 minutes
- Student Handout
- Periodic Table
- No specific safety precautions need to be observed for this activity.
- This puzzle was created to appear in the March 2022 ChemFun section of Chemistry Solutions.
- Below is an overview of the rules for solving a Kakuro puzzle for reference. These are also included on the student handout:
- To solve a Kakuro puzzle, fill-in all the empty squares with numbers 1 to 9 so that the sum of each horizontal row equals the clue on its left and the sum of each vertical column equals the clue on the top.
- Additionally, no number in the same column can be used more than once, and no number in the same row can be used more than once.
- Some puzzles provide numbers in squares to help get you started. Any greyed-out square is not for use.
- Since this is a chemistry themed Kakuro puzzle, you must first determine the numbers associated with each clue by finding the atomic number for each of the element symbols used in the puzzle.
- An example puzzle that includes step-by-step information for students to review is included on the student handout.
- There are two puzzles included with this activity, however many more can easily be found online.
- If students are having difficulty, you can share some Kakuro solving strategies with them.
- Additionally, providing extra starting numbers within the puzzle could be helpful depending on the ability level of the students.
- Two versions of the student handout are available. One has a teal color used throughout the puzzle to indicate which squares require a number in order to solve the puzzle. This puzzle might be best if it is shared digitally. The black and white version of the student handout doesn’t include any shading/color in the squares that require a number. The black and white version is best for printing.
- An Answer Key has been provided for teacher reference.
For the Student
To solve a Kakuro puzzle, fill-in all the empty squares with numbers 1 to 9 so that the sum of each horizontal row equals the clue on its left. The sum of each vertical column equals the clue on the top. Additionally, no number in the same column can be used more than once, and no number in the same row can be used more than once. Some puzzles provide numbers in squares to help get you started. Any black square is not for use.
Since this is a chemistry themed Kakuro puzzle, you must first determine the numbers associated with each clue by finding the atomic number for each of the element symbols used in the puzzle.
Solving the puzzle:
- First determine the clue numbers using a periodic table to find atomic numbers for each element symbol. This is shown in the example on the right.
- The puzzle started with several numbers already given. Use those as hints to get started.
- Look at the first vertical column clue of “5”, in combination with the “4” given in the puzzle. You can solve the first column by using a “1” underneath the “4” to equal the clue sum of “5”.
- Next use the first horizontal row column clue of “13”, in combination with the “4” already filled in. You can solve the first row by using a “9” next to the “4” to equal the clue sum of “13”.
- Continue to use this logic to complete the sums of each row and column. Remember that numbers cannot be used more than once within a column or a row.
- The final solution for this example puzzle can be seen on the right.