Common Core Standards
Grade 1
Reading RF.1.3.G
Recognize and read grade-appropriate irregularly spelled words.
If there's something English tends to do, it's (1) create a "tried-and-true" rule and (2) create a long list of exceptions to go with it. If young readers can turn some of these irregularly spelled words into sight words early on (like walk, two, and would), it'll make the rest of the goin' easy.