What you will need for this project:
1 pair of old jeans
2 pieces of 2" long elastic
2 pieces of 4" long elastic
Start by cutting up the inner leg seam to the crotch and back down again. Don't cut through the inner leg seam, we will be using it.
The pattern is half of one chap leg, used by placing it on a fold of fabric to get a whole chap leg. I am using jeans so I have drawn the other half back on.
Measure your kids side seam length (waist line down to ankle) and cut the appropriate size out. Pin the pattern to the jeans centering the side seam of jeans on pattern and cut out.
Cut out and save the pockets and that inner leg seam strip you saved earlier. Make sure that you cut out the back of the pocket as shown above right pocket. I am using the pockets for my son who has to have pockets on everything, you don't have to have them if you don't want pockets.
This is what you should have so far:
2 chap legs
1 long inner leg seam strip
Zigzag stitch around the chap legs starting at bottom edge stitching all the way around to the other edge.
Pin down 1 1/2" of the tops of chap legs and straight stitch 1/4" above zigzag stitching leaving edges open.
I added some of my own decorative stitching to the pockets after picking out the old stitching.
Pin and sew pockets down in the place where you would like them to be. Mine are 4" down from the top centered on the seam, so that my son's hands just fit in to them.
Lace the inner leg seam strip through the open edges of both chaps. Position them both 1" from either edge of the middle and sew only those edges down (click on picture above to see closer).
I tried these on my son to get the positioning of the elastic strips right at mid thigh and at the ankle. Once you have the positioning right pin the elastic to the chaps (2" pieces on thigh and 4" pieces at the ankle). Sew the elastic on and your done.
The inner leg strip will wrap around the waist and tie in the back as shown above. Since the chaps are only connected to the strip at the back middle you can adjust the waist by scrunching it for smaller waists or leave it flat for larger waists.