Eye See... Multiplicity
Students will be able to multiply multi-digit whole numbers using the standard, partial product, and array model methods.
Introduction (15 minutes)
- Display the cover slide, and let students know that today's lesson will be about multiplication methods.
- Go to slide 2. Challenge students to solve the multi-digit multiplication problem on the slide (225 x 12) in as many ways as they can. Give students 5-7 minutes to work on this task, and remind them to provide a written explanation for each method they use.
- Allow each student to share his responses with a partner.
- Have a few volunteers to share their methods with the class. They may show their work on the board if needed. (Don't reveal the answer to the problem just yet; students will re-visit it later at the end of the lesson.)
- Let students know that today's lesson will teach them at least three different ways to solve this equation.
Explicit Instruction/Teacher Modeling (20 minutes)
- On slide 3, conduct a place value review with the class. Ask students to identify numbers in the ones and tens place of different multi-digit numbers. Make sure to emphasize that single-digit numbers always belong in the ones place.
- Go over slide 4, and use the board to model the standard multiplication method.
- Distribute a sheet of practice problems to each student.
- Have the class complete practice problems 1-5 using the standard method.
- Ask for volunteers to share and explain their answers.
Guided Practice/Interactive Modeling (35 minutes)
- Go over slides 5-6, using the board to model each multiplication method. On each slide, show the videos prior to modeling.
- Have students solve problems 1-5 again, using the partial product and array model methods.
- Remind them that the partial product method involves separately multiplying the single digit number by the numbers in each of the place values. Refer back to the example on slide 5. 6 is multiplied by 7, 50, and 300. The products—42, 300, and 1800—are then added together to determine the final product.
- Remind them that the array model method is similar to the partial product method, but involves using boxes to separate the numbers. Refer back to the example on slide 6. The factor 63 is represented as two columns: 60 and 3.
- Circulate the room, and provide assistance as needed.
- Once they finish, have them check to make sure that the three answers they gave for each question are the same.
Independent Working Time (40 minutes)
- Have students partner up and work on practice problems 6-10. They should use all three methods for each problem.
- Allow a student to ask you questions only if both him and his partner are unable to figure something out.
- Enrichment: Advanced students can work on practice problems 6-10 independently instead of in pairs.
- Support: Have printed copies of slides 4-6 available. Allow struggling students to use them as reference guides.
An interactive whiteboard may be used to model the solutions for various multiplication problems over the course of the lesson.
Assessment (15 minutes)
- Once students have completed their sheets, call on students to come up to the board and model solutions for different problems.
- Observe the students to gauge how well they understand the different multiplication methods.
- Collect the practice problem sheets, and review them later to identify any difficulties that students may have with the lesson content.
Review and Closing (10 minutes)
- Ask students to write a few paragraphs identifying and explaining the three multiplication methods they learned about today.
- Encourage them to include statements on situations in which they would use each type.