1. For one plaid block, gather a set of four 1-1⁄2x2-1⁄2" rectangles and four 1-1⁄2x3-1⁄2" rectangles from one print, four 2-3⁄4" squares from a second print, four 1-1⁄2x3-1⁄2" rectangles from a third print, one 1-1⁄2" square from a fourth print, four multicolor plaid large triangles, and four multicolor plaid small triangles.
2. Referring to Diagram 1, sew a print 1-1⁄2x2-1⁄2" rectangle to a short edge of a plaid small triangle. Add a matching print 1-1⁄2x3-1⁄2" rectangle to adjacent edge of small triangle to make a triangle segment. Press seams toward rectangles.
3. Place triangle segment on work surface with wrong side up. Position edge of an acrylic ruler at seam intersection, aligning 45-degree line with a short edge of multicolor plaid small triangle (Diagram 2). Use a pencil or chalk marker to draw a line along edge of ruler.
4. With right sides together, place a print 2-3⁄4" square under triangle segment, aligning corners (Diagram 3). Sew on marked line. Trim 1⁄4" from seam and discard excess fabric. Press open attached triangle, pressing seam toward triangle. Referring to Diagram 4, trim attached triangle even with edges of triangle unit to make a side unit.
5. Repeat steps 2–4 to make four side units total.
6. Referring to Diagram 5, lay out side units, print 1-1⁄2x3-1⁄2" rectangles, and print 1-1⁄2" square in three rows. Sew together pieces in each row. Press seams toward print rectangles. Join rows; press seams toward middle row. Referring to Diagram 6, trim side units even with edges of joined rows to make a block center.
7. Sew multicolor plaid large triangles to opposite edges of block center (Diagram 7). Add multicolor plaid large triangles to remaining edges to make a plaid block. Press all seams toward large triangles. With block center centered, trim block to 9" square including seam allowances (Diagram 8).
8. Repeat steps 1–7 to make five plaid blocks total.
9. Using light blue print triangles instead of multicolor plaid, repeat steps 1–7 to make four blue blocks.