The worksheet titled "Four Digit Addition Puzzle: Fill in the Missing Addends" is a puzzle-style worksheet that requires students to find the missing numbers in addition problems that have four addends. Each problem is located in a box with the answer in the middle and four smaller boxes on each of the four sides. The four smaller boxes are filled with the numbers that add up to the answer in the middle.

Boxes have overlapping sides, so some problems share the same addends. There are also special rules to help students find the correct answer. For example, one rule is that one of the four numbers has to be a 1, 2, or 3, while the other three numbers have to all be different and must be a 4, 5, 6, or 7. There are also clues that are specific to each addend to help students find the right number, like "less than 7" or "greater than 5."

Puzzles get more difficult as the worksheet progresses with bigger numbers and decimals and addends with negative numbers to challenge students' thinking.

Using puzzles and brain teasers can be a fun way for students to practice things like addition that tend to get repetitive over time. Using a brain teaser also enables them to think outside the box and approach simple math problems from new angles, increasing their problem-solving and critical thinking skills.

For example, solving traditional addition problems can get boring for students over time, but solving multi-digit addition problems where students have to find the addends based on previous addends makes things more interesting. Sudoku-style puzzles are a fun way to practice math concepts, as are crossword-style puzzles where students have to find the missing numbers in blank boxes.