3.2: How Many Pounds
Look at the pictures below.
Can you figure out the total number of pounds for the scale in the third picture (C)? In this concept, we will practice finding the total weight of collections of blocks.
Guidance
In order to solve the problem above, use the problem solving steps.
- Start by describing what information is given.
- Then, identify what your job is. In these problems, your job will be to figure out the total weight of the blocks in the third scale.
- Next, make a plan for how you will solve. In these problems, write the weight of each block on the block and then add the weights together to find the total weight.
- Then, solve the problem.
- Finally, check your solution.
Example A
Figure out the total number of pounds. Write the number on the scale.
Solution:
We can use the problem solving steps to help us with this problem.
Example B
Figure out the total number of pounds. Write the number on the scale.
Solution:
We can use the problem solving steps to help us with this problem.
Example C
Figure out the total number of pounds. Write the number on the scale.
Solution:
We can use the problem solving steps to help us with this problem.
Concept Problem Revisited
We can use the problem solving steps to help us with this problem.
Vocabulary
Substitution is when you replace one object or value with an equal object or value. In this concept, we used substitution when we recorded the weight of each block on the actual block.
Guided Practice
Figure out the total number of pounds on each scale. Write the number on the scale.
Answers:
- 20 pounds
- 18 pounds
- 22 pounds
Practice
Use the following picture for problems 1-3.
Figure out the total number of pounds. Write the number on the scale.
Use the following picture for problems 4-6.
Figure out the total number of pounds. Write the number on the scale.
Use the following picture for problems 7-9.
Figure out the total number of pounds. Write the number on the scale.
Use the following picture for problems 10-12.
Figure out the total number of pounds. Write the number on the scale.
Image Attributions
Description
Learning Objectives
Students determine the total weight of various collections of blocks by recording the weight of each block and adding these weights together. They will use the problem solving steps to solve. This is an early introduction to the concept of substitution, a key skill in algebra.