The worksheet titled "Adding and Subtracting Ones and Tens: A Fill-in-the-Numbers Puzzle" is all about adding and subtracting 1 or 10. The first part of the worksheet displays two boxes with one blank box. If the boxes are horizontal, students subtract or add 1, depending on the directions. If the boxes are vertical, students subtract or add 10, depending on the directions.

Once they have had a chance to practice simple two-box problems, more boxes are added to the mix. Students work on sets of three boxes, as well as diagonal boxes, following the same rule where horizontal boxes are 1 more or 1 less and vertical boxes are 10 more or 10 less. Eventually, they fill numbers in puzzles with multiple boxes in different configurations.

Adding and subtracting 1 is a great way to help students understand number order and develop mental math skills that they can then apply to other methods of counting, like counting by 2, 5, or 10. Instead of inviting students to explore these concepts through traditional addition and subtraction problems, you can help them develop their visual math skills by using puzzle-style problems.

For example, students can see a series of two boxes, one of which is blank. They must fill in the blank box by adding or subtracting 10 if the boxes are vertical or adding or subtracting 1 if the boxes are horizontal. As they get to practice, puzzles can become more complex, with multiple boxes arranged in different configurations. Students use the number clues in the boxes to fill in the blank ones.

Students can also practice this concept by writing 5 more and 5 less in columns on either side of a number, for example. Playing a game with dice where students add 10 more or even 100 more can also be an effective way to practice counting up and down in groups.