Besides the pedagogical reasons I tell them they are like kindergartners, the comparison also allows me to have a little fun in the first few days. I have found two great children's videos on YouTube that teach greetings. They are designed to appeal to young children, but after telling my students that they are like kindergartners, they don't complain when I show them the videos.
Both of these songs have great vocabulary that they students need to memorize in the first few days. The second one goes beyond the first few days and helps the students learn words in context that won't be vocabulary for a few more weeks. The first time I showed them, I was nervous that the kids would be horrified that I brought such baby songs to their class, but in fact, the opposite was true. They love them! They sing them along with the video after a few repetitions and were sad when I told them we didn't need to watch them in class anymore because we were moving on. Even at the end of the year, they remembered them and could sing along.
Music appeals to auditory and musical learners. I know I am both of these and I can clearly remember the Spanish song that my 2nd grade teacher taught me. I didn't know what the song said until years later when I learned Spanish formally, but I was able to translate it because I remembered the sounds of the lyrics even though I didn't know the words. Though not ever student will have as powerful of a memory with a song as I did, some will, and learning these silly songs helps introduce the students to vocabulary and Spanish language sounds while also setting up a tone for the class which will continue to use music and YouTube videos from time to time, even if they are really for kindergartners.
~ La profesora