Free Number Puzzle!
Turning decimals into a fun, Sudoku-like puzzle is a great way to help students work their way through the different decimal operations.
I love solving Sudoku puzzles using whole numbers, and I encourage students to work on them as well. But when I replace the whole number with decimal problems, I’m able to create a logic puzzle that also gives students a new way to practice skills that can be a challenge to master.
Sudoku puzzles are fun and interesting. They require students to problem solve, in order to ensure that every row, column and group of squares only has one of each number. Some students develop strategies when approaching a puzzle; some learn to use guess and check quite often:-)
When working with decimals in a Sudoku puzzle, students need to consider their target numbers, as well as how to complete the necessary operation. This makes decimal practice a bit more interesting and engaging than working on one problem after another on a worksheet.
As with whole number Sudoku, I start decimal Sudoku with a few squares filled in, so students have a starting point. (If students have never tried Sudoku puzzles before, I recommend starting with a regular Sudoku puzzle, to teach students how they work.)
So far, I’ve only used a 4 X 4 grid, which makes figuring out the target numbers fairly easy. All of the squares have a decimal problem with a missing addend in them (in this example). Within each 2 x 2 section, there is one completed problem, with the target number of 1, 2, 3, or 4 already filled in. The object is for students to figure out the target number for each square and then find the missing decimal number in each individual square. Every row and column must each contain 1, 2, 3 and 4 as the answers to the decimal problems (these are the target numbers). Every 2 x 2 section must also contain 1, 2, 3 and 4.
For example, on the answer key shown here, you can see the target numbers of 1-4 in each row, column and section, and you can see the completed decimal problems. Everything in black (target numbers and decimal numbers) is given. Everything in green is what the students must find (target numbers and missing decimal addends):
I've only used the addition problems (which actually require them to subtract:-), but I plan to try the other operations as well and create larger puzzles (6 x 6 and maybe 9 x 9).
To make students really think things through, I may mix up the operations! For instance, in a 4 X 4 puzzle, the first column could be two multiplication problems and two addition problems. This should keep students paying close attention.
These could be great to complete on mini dry erase boards - easy to erase any guesses that don't work out!
Hi, I'm Ellie! I've been in education for 25 years, teaching all subject areas at both the elementary and middle school levels.