Watch the Modal Study #2 online guitar lesson by Jon Finn from Modal Rock Soloing
Here Jon demonstrates the Ionian scale and discusses its characteristics: C Ionian is simply a C major scale. Just play all the white keys on the piano from C to C. C Ionian is a C major pentatonic scale with a 4 (F) and 7th (B) added. If you want to convey a distinctively Ionian sound, including the 4th degree (F) makes it sound not Lydian and including the 7th degree (B) makes it sound not mixolydian. Both notes are needed to convey a true Ionian sound. After going through all this material, reviewing will be very helpful if you don't understand it all the first time.