I incorporated my different tone of voice to the children when I am delivering my therapy session. Owing to the need to include very specific volume and inflection of voice when communicating with them, I have some experience varying my pitch, making my voice more animated and fun for the children to follow. For example, when they got correct for that lesson, I would cheer particularly loudly with a joyful voice to them. When they did not get it correct, I would mellow down my voice to a rather neutral tone so that they know they got an incorrect answer.
I did not get any specialized training on voice over, but I have plenty of experience varying my tone from super high pitch to low pitch, loud to soft volume as well as from the most animated voice to a neutral tone.