It is not easy for a young child to comprehend multiplication by 1, as how they are taught in school is often the robotic multiplication table. She or he can very quickly answer mutiplications by 2, or 3. Because of this, questions like “what is the product of 1,2, 3, 4” (i.e. 4 factorial) can get a wide range of answers because the number “1” confuses the young mind.
Pychologist says that an infant learns the number 2 before the number 1. And we can see why: with 2, there is something to compare against, like two fingers. If there is only one finger, there is no variation, it is confusing.
When we teach multiplication, don’t forget to show that math is an integral part of the real world around us. It is invented to simplify addition. Multiply by 1 means just the thing itself. Multiply by 2 means adding two of this thing together. Multiply by 3 means adding three of the thing together. The thing can be a bag of candies or the footage of a home.
Finally, we should show children how to use computers (not calculators) to do computations. While a question like “give me the sum from 1 to 199” can be solved within seconds with math tricks, a slightly different question “give me the product from 1 to 199” won’t work with the same trick. But if you know how to make the computer do the job, you can still answer it within seconds.