This is definitely true. I even hear adults say that they end up using easier words so they can avoid words they don't know how to spell!! I remember in high school (over 20 years ago) that I spelled the word "grammar" wrong on an assignment. I tended to write very quickly and did not take the time to review my work. I just wanted to get everything written before the bell so I didn't have to take work home. The teacher wrote the correct spelling on my paper (IN BIG RED LETTERS) and told me that now I will never forget how to spell it!! She was right!!! Because she pointed it out so clearly I never forgot!