At the end of the Seder we sing Echad Mi Yodeia. The song is written in question and answer form: “Who knows one? I know one. One is Hashem in the heaven and the earth. Who knows two?…Two are the luchos…” and so on.
The Sheim Mishmuel zt’l asks, why does it need to be with questions and answers? It could have simply stated, “One is Hashem, two are the luchos, three are the avos,” etc. The Sheim MiShmuel explains that this song is a test. At the end of the Seder, we want to see whether we’ve acquired the lessons that the Seder teaches us. We ask, “When I say one, what’s the first thought that comes to your mind? Is it ‘one hundred dollars’? Is it some other materialistic factor, or is your first thought Hashem is one?”
We go through the numbers from one to thirteen and ask the family, what’s your first association when you hear these numbers? If we acquired the lessons of the Seder correctly, we should be able to answer: One is Hashem. Two are the luchos. Three are the avos, because we realize that only these matters are important, everything pales in comparison. ~ R’ Elimelech Biderman Shlita