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General
Students learn to subtract numbers to 10.
Common core standard
1.OA.A
Relevance
It is important for students to learn how to subtract to determine how many they have left.
Introduction
The intractive whiteboard shows a laundry line hanging and numbered jerseys from 1-10 below. As a class, hang the jerseys in numerical order. Be sure to name each number as it is hung, and to mention the numbers before and after the number.
Development
The learning goal is explained visually, in the abstract, and as story problems. You can choose which method to discuss with your class by using the menu in the bottom right of the page. The lesson starts with a visual explanation. Explain to students that they can see how many objects are in a first group and then count how many are taken away to find the difference. Make sure to emphasize that the total number that they see is the first number (minuend) of the subtraction problem, and the second number (subtrahend) is the amount that is taken away. Practice this with a few subtraction problems.
Subtraction is next presented in the abstract. If the numbers do not have visual support, students can use blocks, or a rekenrek to calculate the difference. Students can also use a number line to solve the subtraction problem. Discuss that you can choose which method of solving you like best, including subtracting a smaller number twice, or other approximation strategies. Practice with a few subtraction problems and be sure to ask students how they found the difference.
Finally discuss with students how to solve subtraction in story problems. There are steps to take to make sure you get all the right information for your subtraction problem. First you must decide what kind of math problem is in the story. Next, you must determine which numbers are important for the math problem. Then students need to say or write the problem and finally to solve the problem. Practice with a few story problems in class.
Check that students understand subtraction to 10 by asking the following questions:
- What happens when you subtract? (you take away)
- Can you swap the numbers in a subtraction problem? (no, you can do this in addition)
Guided practice
Students first are given a subtraction problem with visual support. They then are given a subtraction problem without visual support and finally are given a story problem to solve.
Closing
Discuss why it is important to be able to subtract numbers to 10. To close, practice various subtraction problems with numbers to 10.
Teaching tips
Students who have difficulty with the abstract problems can make use of the rekenrek, blocks or other manipulatives.
Instruction materials
optional: rekenrek, blocks or other manipulatives
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About Gynzy
Gynzy is an online teaching platform for interactive whiteboards and displays in schools.
With a focus on elementary education, Gynzy’s Whiteboard, digital tools, and activities make it easy for teachers to save time building lessons, increase student engagement, and make classroom management more efficient.