Making quilt can be as simple or complicated as you want. This is a simple 9 patch.
First choose the size of the quilt you wish to make--you can measure the bed you wish to cover, remember to allow if you want to tuck it in.
The next step is to plan the quilt. For example, will a border take up part of the widths or are your squares going to the edge? Will you use biased tape or do you intend to turn the edges under (requiring a few extra inches) to make the edges?
Let's say we're making a 35" square baby quilt. There will be 12 nine patch blocks and 13 solid blocks (some of mine were printed marked 'r' and others where white, hence the markings on my paper). I decided on one 5" border, rather than the two I originally had planned.
I sketch it out on quadrille paper so I can decide upon a pattern.
I decide my finished squares will be 5". I add 1/4" per side (not per width or height), so I will cut 5 1/2" squares. For my 9 patch blocks, I divide 5 (from the size of my finished squares) by 3 (as the patch will be 3 blocks wide by three blocks high) and then add 1/4" per side, for 2 1/16" square. (These sizes are totally arbitrary, just pick the size that works for you--smaller squares require more sewing, but allow for smaller pieces of fabric and more designs.)
large block = x = 5" squared
block for 9 patch = y = x/3" squared + .25" squared + .25" squared
And maybe you thought you'd never have any use at all for basic algebra and geometry after high school!
** I'll post about more steps next week! **