Video Transcript
Which equation describes the number of dots in this model? Is it three multiplied by five equals 15? 15 divided by three equals five? Five plus three equals 15? Or 15 divided by five equals three?
Let’s think about what the model shows. The model shows three groups of dots. How many dots are there in each group? One, two, three, four, five. The model shows three groups of five. We could find three groups of five by counting in fives along a number line. One jump of five takes us to five. Two fives are 10. Three fives are 15. So, we know that three groups of five equals 15.
Which of our expressions is the same as saying three groups of five equals 15? It must be one of these two expressions. They both give a total of 15 dots. The first expression says, three multiplied by five equals 15. We know we have three groups of dots. And we also know that each group contains five dots. Three multiplied by five is the same as saying three groups of five. And we know that three groups of five, or three jumps of five on a number line, equal 15.
The equation which describes the number of dots in the model is three multiplied by five equals 15. Five plus three equals eight, not 15. So, we know that this equation is not correct. And we know the other equations are not correct because they didn’t give a total of 15 dots. The model shows three groups of five dots. Three groups of five is 15. So, the correct equation is three times five equals 15.
