Objective: Learn and correctly use the essential sewing vocabulary and MC6650-specific terms you'll rely on throughout the course and in every pattern you follow.
Patterns, tutorials, and the Janome manual all assume you know a shared vocabulary. Master these now so instructions make sense later. Seam allowance is the distance between your stitching line and the raw edge of the fabric; most patterns use 1/4" or 5/8", and the MC6650's needle plate has guideline markings to help you hold it steady. A backstitch (or reverse stitch) is sewing a few stitches backward at the start and end of a seam to lock the thread so it won't unravel; the MC6650 has a dedicated reverse button and a lock-stitch button for this. Feed dogs are the metal teeth under the presser foot that grip and pull fabric through at an even pace, so you guide rather than push fabric. Stitch length controls how far the feed dogs move per stitch (longer for basting, shorter for strength); stitch width controls side-to-side needle movement for zigzag and decorative stitches. The presser foot holds fabric down against the feed dogs, and the MC6650 lets you swap feet for tasks like zippers or buttonholes. Thread tension balances the top thread and bobbin thread so stitches lock inside the fabric rather than looping on top or bottom. Bobbin is the lower spool of thread; the MC6650 uses a top-loading drop-in bobbin. Topstitching is visible decorative/functional stitching on the right side, and basting is long temporary stitches to hold pieces before final sewing. Knowing these means you can read "stitch a 5/8" seam, backstitch at both ends" and act with confidence.
Example: Imagine a pattern for a zippered pouch says: "Sew the side seams with a 1/4" seam allowance, backstitching at the start and end." Translating: set a straight stitch, align the fabric's raw edge with the 1/4" guideline on the needle plate, press the reverse button for 3-4 stitches, release and sew forward along the guideline, then press reverse again at the end. The feed dogs pull the fabric; you only guide it. Those locked seams keep the pouch from coming apart when a customer uses it.
Try it: Without the manual, write out your own one-sentence definition for each of these ten terms: seam allowance, backstitch, feed dogs, stitch length, stitch width, presser foot, thread tension, bobbin, topstitching, basting. Then find and physically point to the reverse/lock-stitch button, the drop-in bobbin area, the presser foot, and the needle-plate seam guides on your MC6650.