Answer
This is a writing exercise for the student, and answers will vary.
Sample: Hi Grandpa and Grandma! I used to think that temperature and heat were almost the same thing. I now know that heat is just energy in transit, traveling from a high-temperature object to a low-temperature object. An object doesn't contain heat; it contains internal energy. And temperature isn't even an energy at all - it just measures how fast the molecules in something are shaking.
Mind blown.