I agree, you need a new ruler.
If wonky seams are an issue, you might need to verify your quarter-inch seam. Does the Craftsy class demonstrate that also? If not, you might google for some tutorials. Tip - don't measure the seam allowance on the back of the patches you sew. Instead, cut 2 patches that are each 1" wide and sew them together. Press your seam (doesn't matter if it's open or to the side) and measure the right side of your fabrics. It should now measure 1.5" wide. If not, then your seam allowance is off and you need to adjust.