Gather students and ask them to pay attention to the 5's column and the 5's row. Remind them to look for patterns in the products. Using the vocabulary is critical according to the Common Core. Make sure to guide the responses to the 0, 5, 0, 5 pattern. After conversing about this pattern, have the students view the video below. It is a fun video to drive the product pattern home.
Yesterday we explored counting by 5's. Watch this video and look for the patterns in the one's place. Also, watch for the word "product". We will be discussing this vocabulary word later.
After the video, discuss with the students how using this pattern can help them be more precise in their work.
Mathematicians, we have talked about a pattern of 5, 0, 5, 0 in the products of multiplying by 5. We have now just heard a fun song reminding us of that pattern. Can you turn and talk with your partner about how that can help you when you are multiplying by 5?
Great! I think it is a wonderful idea to know that when you are multiplying by 5, the product will have a 0 or a 5 in the one's place. If there is a different number, you know there was a mistake somewhere.
During this part of the lesson, you may want to try to pull students further into the patterns of multiplying by 5's in base 10.
Boys and girls, can anyone figure out why every other 5's count by is a ten's number?
Following this question, you may want to ask the students to discuss with their table groups, turn and talk, or even journal their thoughts. I chose to have them discuss at table groups and share out. What you want to watch for is the understanding that 2 5's makes a ten, therefore, every other count by is a ten.
Next, have the students list the 5's multiplication facts, or look at the class table.
Now, can you look and see any patterns in the products of the 5's count by's?
What other patterns do you notice? Would the picture of 5x2=10 look different from 2x5=10? Why do you agree or disagree.
Counting by 5's is a fairly easy task for students. This is a great time to show them how to keep track of the count by's with their fingers and to use that number on their hands to write an equation.
Students, when we count by 5's, let's keep track of our skip counts with our fingers. This will help us figure out the other factor in the equation. Remember, factors are the numbers we multiple. 5 is our group size and the number on our fingers will be the amount of times we count the 5's.
After some practice, I give the students the product and see if they can solve for the missing factor. They can use their fingers and count up to the product by the factor 5.
You may want to make sure the students get a chance to solve multiplication equations with each other. This is a good time to have them work with flash cards and their finger strategy, or they could use a deck of cards and always have one of the factors be a 5.
I like to have the students use a mixed list of the facts and quiz each other. This enforces both of the student's practice time, whether they are the questioner or responder.
Beat the Calculator is a great game and the one I have chosen to send home as homework. You might want to check it out here.