This is a modification of the Helping With Math tasks, "Number Grid Puzzles," https://www.helpingwithmath.com/printables/worksheets/numbers/1nbt4-number-grid-puzzles01.htm. This activity was used with a tier 3 fourth grade intervention math group to help students count by tens in mid-decades and count forward and back by ones. I modified this activity by first having students make observations and note patterns in a hundreds chart; specifically encouraging students to note that counting on by ten ones increased the tens digit by one. Students then modeled this concept with base-ten blocks. Finally, students completed the hundreds chart number puzzles to reinforce this concept and wrote matching equations when a puzzle was solved. For example, "47 = 35 + 12."