Today’s lesson is an additional practice for students using the standard algorithm for multiplication. To me this is ‘old school’ multiplication; the way I learned. I definitely see value in teaching students the partial products and lattice method in earlier grades but no one can argue that the standard algorithm is much faster.
I entice the students back into multiplication today by offering them another competition.
Alright, I won the competition yesterday but I’ll offer you guys another chance. This time you can use the turtlehead method or the standard algorithm and I will use lattice. If you guys win this time I will offer you an additional five minutes of recess. Any takers?
I get a few students up to the board and we all write down the same problem; 63 x 42. I tell them to begin and they vigorously begin working on their problem while I take my time drawing the lattice box. Just to add to the fun I mess up the drawing of my box and have to erase part and start again. As I finally finish drawing my box the students begin to finish. I ham it up and act super disappointed and astonished that they were able to win.
I totally thought I had you guys again. Now I have to give extra recess. What was I thinking? I don’t know what I did wrong. What could I have done differently?
I allow students time to laugh and respond to my question. They quickly catch my over the top drift that the standard algorithm is much quicker than the lattice method.
In order to practice the standard algorithm I have students work on story problems using multiplication within their groups. The students will work on six separate problems by rotating through the six tables in my room and completing a story problem at each table. I ask them to get a sheet of paper so that they will be able to write down the problems and show their work for solving them. I place a story problem at each table and have the students begin working. I allow about 3-5 minutes per table and then announce switch so that they move to the next table with their group.
After groups have rotated through all six tables I review the problems with the students. For each problem I have a student come up to the whiteboard and explain how they solved the problem.
The final activity within this lesson is an adaptation of game I found in the Georgia Department of Education standards framework. The students play tic-tac-toe with a multiplication board in which the spaces the product of two numbers. Students must choose a number from box a and another number from box b. They need to multiply the two numbers together to find the product. The product can be found on the gameboard and the student is able to mark the space of the problem they just solved. Once a student gets three answers in a row, column, or diagonally they win the game.
I find this game to somewhat challenging to the students. There is definitely some strategy involved in estimating the product of the two numbers chosen.