Sum Slider

Sum Slider looks like the sliding puzzle you already know — numbered tiles in a grid with one empty space, and a tile can only move by sliding into that space. What changes is the goal. You are not restoring numerical order; you are arranging the tiles so that each row adds up to the target shown above the board. The empty space counts as zero, and tile values can repeat.

That makes it a puzzle about sums and about access at the same time. You might see that swapping a 7 for a 3 fixes the top row, then discover that the only route for that 3 runs through the row you already finished. Good players work out which tile has to end up where before they start sliding, and they leave the blank somewhere useful. Boards come in 3x3 and 4x4, and the game counts your slides against a par so there is a reason to find the tidy route rather than the long one.

It suits students who are fluent enough with addition to hold a few running totals in their head, and it quietly drills that fluency: finishing one board means checking dozens of sums without ever being asked to do a worksheet.