Sum to Twenty Puzzle by Marcy Cook

Today I’m sharing with you the Sum to Twenty Puzzle by Marcy Cook.

In Math Concepts, we ran out of That’s Logical puzzles a few weeks ago, so I had to find a new source of daily warm-ups. Instead, I’ve started using puzzles from “THINK ABOUT IT! Mathematics Problems of the Day” by Marcy Cook.

This book was published by Creative Publications in 1982, and for once I would not recommend ordering a copy off of Amazon.

If you already happen to have a copy, cherish it and don’t let anyone borrow it!

Wednesday, I put this sum to twenty puzzle up on the board. And, I challenged my students to solve it on their individual white boards.

This. Did. Not. Go. Well.

Students were confused by the fact that there were already two fours in the puzzle. Students were confused whether they had to use each number between 0 and 9 only once or if they could use some more than once and others not at all.

I ended up encouraging my students to write the numbers 0-9 on their dry erase board so that they could mark off each number as they used it.

This still did not go well. Students were bringing me their whiteboards to check their answers, and it was clear that they had misunderstood the instructions. Many had made each row sum to twenty without worrying about the columns.

These students do tend to struggle more than most. This is part of the reason they are in Math Concepts, a class created for our 9th graders who are not yet ready for Algebra 1.

After telling student after student that their answer was incorrect, I eventually decided we needed to stop this activity and regroup. I told them to put their dry erase boards away with the promise that we would tackle this puzzle again the next day.

A few minutes on the computer and some quality time with my laminator led to a version of this puzzle with moveable pieces.

The next day, my students seemed reluctant to try the sum to twenty puzzle again until they realized that it was in a slightly different form. With the moveable pieces, they jumped into the puzzle with a bit of excitement.

Within only a few minutes, my students started announcing that they had solved the sum to twenty puzzle. It was adorable to watch them attempt to cover their solution from the prying eyes of their classmates. I’ve had issues with this class sharing puzzle answers, so it was especially good to see this.

This was no longer an impossible puzzle but a puzzle with a solution worth working towards.

There’s another variation of this sum to twenty puzzle that sums to 21 in the book that I look forward to trying with my students after this whole strike business is over.

This puzzle would be a great addition to a puzzle table, as well!

Digital Version

Google Slides

Cathy has converted the Sum to Twenty Puzzle to a Google Slide Presentation.

Danita Forbes has also created a version of this puzzle.