This exercise is "meow" on a 1-5 interval.
The "m" brings you into nasal resonance, the "ee" vowel lifts the tongue and brightens the sound and help you to not push out of the mouth. "Ah" gives you a more acoustic, belt-like shape to your mouth, and the "oo" will bring you back into the head.
Focus on steady breath support. Don't get loud to go high. Stay the same breath-wise and volume-wise.
Use nasal resonance in all the registers.