Level 1. BUY, BUS, BUSHY, BUSY
Level 2. ROW, WORK, WORKER, OWE
Level 3. THIS, GIST, SIGHT, SIGH
Level 4. WEAR, WARE, SEAR, SWEAR, SAWER
Level 5. COT, ACT, COST, COAT
Level 6. OUT, TUG, HUG, GUT, HOT, TOUGH, OUGHT
Level 7. EVE, EVEN, ELEVEN, EEL
Level 8. LOP, ILL, WILL, PILL, PILLOW, PLOW
