The thirteenth and fourteenth books in the series, Farm Rescue and River Outing, use decodable regular words made up from all seven groups of letter sounds:
s, a, t, i, p, n
c k, e, h, r, m, d
g, o, u, l, f, b
ai, j, oa, ie, ee, or
z, w, ng, v, little oo, long oo
y, x, ch, sh, voiced th, unvoiced th
qu, ou, oi, ue, er, ar
Tips and guidance for teachers and parents are provided at the end of each book. Light type is used as a guide for those few letters that should not be sounded out, such as the /b/ in ‘lamb’.