Aunt Bev's Old-Fashioned Slippers
This version © Beverly A. Qualheim 2013, 20168 - you may LINK to this pattern and print it out but do NOT post these actual words/instructions or photos, on any other website, in emails or forums etc!
http://www.bevscountrycottage.com/striped-slippers.html

     
This is such an old pattern... handed down to me in it's raw form, on a piece of crumpled paper and I have no idea who originally authored it.  I have seen it referred to as the 'phenex slipper' so perhaps someone at that yarn company wrote it.  I found the original version quite hard to figure out so I knitted a pair and re-wrote the pattern in easier terms.  I've also added photos after the written pattern to help you see what's what.
 It really is a simple pattern to memorize, once you make one slipper.  PATTERN is written in US terms.  

  

Knitting needles: size 8 (5 mm)  for kids, size 10 (6 mm) needles for teens/adults
(Baby booties could be made using size 5 (3.75) needles and sport weight yarn)
3 oz  - WORSTED WEIGHT (#4)  yarn - 2 different colors --one light (1), and one dark (2) I used Red Heart Classic-- turqua and rose pink
Gauge:  size 8 needles: 8 rows = 1", 4 sts = 1"

Cast on 66 stitches with light color. (This will be the heel area)

Row A- outside)  Knit 6 sts with color #1, then add in color #2 and knit 6 sts.   Alternate the colors every 6th stitch across the row, pulling the 2nd color in the back of the 1st. It needs to be pulled a little on the backside to make the puffy rows. (The 'pulled-to tighten' strand needs to be about 3/4" - 7/8" across back of each set of 6 sts.) 

Row B - inside)  Knit the same as row A. Change the colors every 6th stitch across the row, pulling the 2nd color slightly (pulled strand in on the side facing you on this row) to match 3/4" - 7/8".  (See below ***)

Repeat Rows A and B for the length you desire.  

Knit until desired length is reached or approximately:
20 ridges for ages 3-6   (40 rows)
24 ridges for ages 7-11  (48 rows)
30 ridges for ages 12+ (ladies)  (60 rows)  with size 8 needles this makes an 8 1/2" slipper
34 ridges for mens med/large  (68 rows)

4 rows of DECREASE:

1) *Knit 2 together, repeat from *across all the stitches.  (33 sts)
2) Knit across the inside of the slipper (backside)
3) Cast off down to 22 sts by *knitting 1 st, then k2 together; repeat from * across row.
4) Knit across the inside of the slipper (backside)

Cut color #2 (turqua) leaving a 4" tail to weave inside slipper to secure.  Cut color #1 (pink) leaving an 18" tail of yarn for stitching down side.  1st GATHER toe sts tightly and secure.
♥  Now, fold over the long edge 6 sts, which are 'flat ' right now, and stitch down slipper long side to form another ridge, end off by securing yarn, cut yarn. (See photo on left).  Fold over 2nd side and repeat sewing.
♥  Flip slipper inside out and sew heel shut. (Photo on right)
♥ Flip back to the right side and sew across top of slipper to close, leaving enough room to insert foot.
♥  Make a pompom for the top and sew to top of slipper.

HELPFUL HINTS AND PHOTOS

*** As you knit across Row B, make sure the color you are using (we'll call it color #1) is taken to the 'outside/front' of the slipper to knit those 6 sts.   Then bring color #1 back to the 'inside' of the slipper, and move color #2 to the front (as in photo to left)   Don't forget to do this with each color change...

Your working color will be on the outside/right side of the slipper and your non-working yarn will be facing you, on the inside of the slipper.  (See photo on right)

I found that I needed to 'twist' some of the stitches as I changed colors, (See photo below) especially with the first color change of each row, to avoid a small hole.  (By the way, the first 6 sts and last 6 sts of each row remain 'flat' but we will fix that at the end.)