It gets a bit more complicated than that too!
For example the 'n' sound, like in 'nail' is also spelt ‘kn' like in ‘knot’ or ‘gn' like in ‘gnome’.
Still with us?! Good!
The sound that children struggle to spot the most when decoding words and breaking them down into its sounds is the 'split digraph'. This is when two letters work together to make one sound, however they are split by having a separate letter in the middle.
Fortunately ‘split digraphs' always end in an ‘e' which does make them a little easier to spot!