Subject area: Mathematics
Grade level: 3rd Grade
MN math standards: 126.96.36.199- Multiply multi-digit numbers, using efficient and generalizable procedures, based on knowledge of place value, including standards algorithms.
Objectives: For students to form a basic knowledge for 2-digit multiplication and division using a variety of methods.
Time to be used: 40 minutes
List of materials:
- · Smart-board
- · 3 dice per group
- · Notebooks
- · Writing utensils
- · Chips or Foam Counters
Before the lesson:
Before the class starts, the Smart-board should be aligned and load the reconstructed lesson outline. Each table should have dice and counters according to the number of pairs per table, 3 dice and 10 counters for each group. The teacher should address that the dice and counters should be kept in the middle of the table until the teacher says to grab them. The students will be asked to sit in the front of the class with their math notebooks to take notes on the different methods that will be shown.
During the lesson:
The first concept that will be covered is Multiplication. Showing the first slide of the Smart-board lesson, the teacher will show how to roll the dice (press on each die). These are the numbers that will be used to demonstrate how to use each method. The first two dice will make the 2-digit number and the last die will be the single-digit number ex: a 3 and 2 will become 32 to be multiplied. The first method to be cover is the Complete-Number Strategy found on page 227, figure 12.15. This method shows “repeat addition” and this is the process of taking the larger number and adding repeatedly to get the correct answer. Ex: 23 * 3 becomes 23 + 23 + 23, see figure 12.15 for correct layout of the problem. The teacher will show this process on the second slide of the Smart-board lesson. Using the same numbers the teacher will move on to the Partitioning Strategy by decades found on page 227, figure 12.16.
The teacher should then go back to the first page on the smart-board to the dice activity. Press on each dice and write in the blanks the equation. Ex: you rolled a 3, 4 and a 7…this would be 34/7. The teacher should then go to the fourth smart-board page and explain to the students how to do the model on page 234, figure 12.24. The numbers on the side indicate the quantity of the divisor being subtracted from the dividend. Write the whole problem out on the smart-board and have the students copy it in their notebooks. Have three student volunteers come up and roll the dice again up on the smart-board (page one.) The teacher should then go to the fifth page and explain how to do the explicit trade strategy found on page 236, figure 12.25. Fill in the smart-board with the problem and have the class participate by writing in their notebooks as well as helping find the answers with the teacher.
After the lesson:
Activity: Dice Wars
The concept of Dice Wars is for groups of 2 to practice the different concepts of multiplication and division. Each group will get 10 counters or chips to tally their points. They will be given 3 dice to use. As shown in class the students will roll the firsts 2 dice and combined the numbers ex a 2 and a 3 becomes 23 or 32. The students will then roll the third die to find what number they are multiplying or dividing. The goal is to be the first one to solve the problem, whoever solves the problem first gets a point. Students will get 1 chip for each round they win, they must use each method once and they must solve 3 multiplication and 2 division problems in order to win.
Assessment: The teacher will monitor the students playing the dice war game and evaluate their participation. Students should have at least three strategy problems worked out on their notebook paper as well to turn in.
Closure: Today we learned different methods to multiply and divide 2-digit numbers but tomorrow we will try the same methods with 3-digit numbers.