Number Walls to 20: Addition Pyramids with Missing Bricks

This 1st grade number-walls worksheet — some teachers call them addition pyramids — lays out six small brick walls, three courses high. The bottom row of each wall is printed with three numbers, such as 6, 3, and 8. The two bricks above are outlined in dashed orange and empty, and so is the single brick at the top. The rule is written once at the head of the page: each brick is the sum of the two bricks under it. The child adds 6 and 3 to fill the left brick, 3 and 8 for the right, then adds those two answers together to set the top stone, and moves on to the next wall.

A number wall turns three separate addition facts into one small structure, and that structure is what makes it different from a plain column of sums. The top brick can only be right if both bricks beneath it are right, so an error in the first row travels upward and shows itself, which teaches the child to check as they go. All the sums stay within 20, the fluency range for this grade, and the bricks are big enough for a child to write the number and still see it. The teacher watches whether the child adds the middle base brick twice — once to the left, once to the right — without confusion, since that shared brick is the part that surprises children the first time.

Print the PDF free and let the child use a number line or counters for the first wall, then try the rest without. The easier version has four walls with sums to 10; the harder version builds four-course walls of ten bricks and knocks a brick out of the base, so the child has to subtract downward from a given brick above to recover the missing number. Number bonds to 10 is the page before this one if the child is still learning the pairs, and doubles and halves works the same fact range from a different direction.