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Author:
CHRIS BRENNAN

This tutorial covers Math in Focus Lesson 12.1 (Real-World Problems: One-Step Problems). I begin by "recalling prior knowledge" about bar models and then move on to using bar models and addition, subtraction, multiplication, and division to solve real-world problems.

In Student Book 3A, students have learned addition, subtraction, multiplication, and division of numbers up to 1,000. They have mastered the four operations using standard algorithms. Students have also learned how to use bar models to solve one-step and two-step real-world problems. Students have been taught to choose the correct operational concepts to solve real-world problems involving part-whole (in addition and subtraction), adding on, taking away, comparing, multiplying, and dividing. In order to solve real-world problems on measurements, students need to be proficient in conversions between the units of measures.

Drawing the various bar models allows students to think about how the given information in a problem is related. This understanding will lead students to eventually find a solution to any one- or two-step problem. The part-whole concept is one way of thinking about number relationships. In addition, the parts are put together to form a whole. In subtraction, the known part(s) and whole are used to find the missing part. In multiplication, the equal parts can be combined to find the whole (total). Similarly, in division, the whole can be divided up into equal parts.

Tutorial

This video will show you how to use addition and a part/part/whole bar model to find the answer.

In this problem, I use addition and a part/part/whole bar model to find the answer.

In this video, I use addition and a part/part/whole bar model to find an answer, and then convert the answer from grams to kilograms. Remember: 1000 grams = 1 kilogram!

In this video we use addition to find the answer, and then convert meters into kilometers. Remember, 1 kilometer = 1,000 meters!

Are we adding in this video? No! This problem calls for a comparison bar model instead of a part/part/whole bar model to find the answer.

In this video, I use multiplication and a bar model to find the answer to two different problems.

To conclude Lesson 12.1, I use division and a bar model to find the answer.