About Lesson
Math Lab Activity
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– To perform addition and subtraction of integers using different colored buttons/counters.
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Objective:
To understand the concepts of addition and subtraction of integers.
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Material Needed:
- 10 white buttons and 10 black buttons.
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Procedure:
- Assume a white button as (+1), a black button as (-1) and a pair of one white and one black button as zero [Fig. 8(a)].
- To find the sum of (+5) + (-2), take 5 white buttons and 2 black buttons and arrange them in two rows as shown in the [Fig. 8(b)].
- Match one white button with one black buttons as shown in Fig. 8(c).
- Every pair of one white and one black button makes zero. Count the remaining buttons and note down their color. If remaining buttons are white, answer is a positive integer. If remaining buttons are black, answer is a negative integer.
- To find the value of (+4) + (-6), take 4 white buttons and 6 black buttons. [Fig. 8(d)].
- Follow the Steps 2 to 4. [Fig. 8(e)]
- To find the value of (+5) β (+2), take five white buttons and 2 black bottoms. [Since +2 is to be subtracted] and place them in 2 rows as shown in Fig. 8(f).
- To subtract +2 means adding -2 i.e. 2 buttons of black color. Match the button of two colors [Fig. 8(g)]
- Count the remaining buttons and note their color.
- To find the value of (+4) β (+5) take four white buttons and 5 black buttons. Arrange them in rows as shown in Fig. 8(h). Match the buttons of two colors.
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- To find value of (+4) β (-5), take four white buttons and 5 white buttons and place them
in 2 rows as shown in Fig. 8(i). Count the number of buttons and their color.
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Observations:
(i) In Step (4), the number of remaining buttons = ___________
Their color is___________
So, (+5) + (-2) = ___________
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(ii) In Step 6, the number remaining buttons = ___________
Their color is ___________
So, (+4) + (-6) = ___________
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(iii) In Step 8, the number of remaining buttons = ___________
Their color is ___________
So, (+5) – (+2) = ___________
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(iv) (+4) – (+5) = ___________
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(v) (+4) – (-5) = ___________