Addition is part of everyday life. We add when we shop, when we put items together and want to know how many of something we have. It helps us to make sense of the world around us.
Subtraction is part of everyday life. We use it when we buy our lunch at school. When we have a set of objects that get used, given away, lost, or traded for something else, we can use subtraction to find out what we have left. Subtraction also helps us make sense of the world around us.
Problem solving is an essential part of our daily lives whether it is a math problem or a problem that arises in another area. The better problem solvers we become, the better equipped we are to handle day to day challenges.
When problem solving in math, it is important to eliminate extraneous information and determine what is important for solving the problem at hand.
Once you understand what you are trying to solve it is important to come up with a plan which will help you come to a reasonable conclusion.
Once you plan is developed, use your plan to solve.
I. Sequence of Activities (Instructional Strategies)
Present two containers of marbles to your students and ask them if there are more
marbles in container 1, container 2, or containers 1 and 2 together. Discuss and
ask: What operation you would use to find a number that is greater than?
Now pour all the marbles in container 1and let the students know that there are 50 marbles. Ask one student to take out 10 marbles, and then ask them: Now are there more than 50 marbles in container 1 or less? What operation would you use to find a
number that is less than 50?
B. Instructional activities (demonstrations, lectures, examples, hands-on experiences, role play, active learning experience, art, music, modeling, think-aloud, discussion, reading, listening, viewing, etc.)
1. Objective: The student will learn when to use addition and subtraction to solve a
2. Procedure: The teacher will present situations which require either addition or
subtraction to solve.
3. Modeling: The teacher will demonstrate with student participation using overhead,
1. Ask the students to use their base 10 blocks to build the following numbers on their
base 10 mats (copy included in materials) – 145 and 232
Put the transparency of the story problem below on the overhead.
Taylor and Alex were playing a game. Taylor scored 145 points and Alex scored 232 points. How many points did the two score together?
Ask the students to use their strategies and to ask themselves if they need a number that is greater than 232 or less than 232.
Put base 10 blocks together in the “Total” section to figure out answer ( 377points)
Get student input and explanation and have students write the problem with labels.
Now put the following (transparency 2) of the story problem below on the overhead.
Taylor and Alex were playing a game. Together they scored 377 points. If Taylor scored 145 points, how many points did Alex score?
Have students repeat steps 1-5 making sure that in step one they start with the total and find their parts to find a solution. Ask students, what was different?
Have students write the problem with labels.
Repeat steps 1-5 with transparency 3
Transparency 4 problem 1 guided without using base 10 materials
Transparency 4 problem 2 with partner and check.
Transparency 4 problems 3 – 6 with partner and check.
Close by asking: When you subtract you get a (smaller) number. When you add you get a (larger/greater) number. Ask if someone can give an example of when you may need to add/subtract or to give an example of a problem.
Review day 1 concepts and practice with a partner using Day 2 worksheets.
As partners work together circulate and monitor.
You may choose to have a small group with students who are having difficulties.
Check Day 2 worksheets together using Day 2 Transparencies
Conduct a brief Review using Day Three Review Transparency.
Independent practice – Day Three worksheets
During day 2 when students are working with partners, if some students struggle, the teacher may want to pull them in a small group and work with them. The teacher may choose to let them continue to use the base 10 blocks or other manipulatives that may be helpful in their understanding.
Partners who finish early should make up story problems involving addition and subtraction and then solve.
II. STUDENT PERFORMANCE
The students should be able to solve problems independently using strategies.
Reduce number of problems with reduced extraneous information.