Addition and subtraction (T1 W3)
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Addition is the process of finding the total or sum by combining two or more numbers. For example, if you have 3 apples and you get 2 more, you can find the total by adding: 3 + 2 = 5 apples. Subtraction, on the other hand, is taking away a number from another. If you have 5 apples and you give away 2, you can find out how many you have left by subtracting: 5 - 2 = 3 apples. Both operations are essential for solving everyday problems.
Let's look at an example: If Sarah has 4 marbles and her friend gives her 3 more, how many marbles does she have now? We can write this as an addition equation: 4 + 3 = 7. So, Sarah has 7 marbles in total. We can visualize this by drawing 4 marbles and then adding 3 more to see the total.
Now, consider a subtraction example: If there are 10 cookies and 4 are eaten, how many cookies are left? We can represent this with the equation: 10 - 4 = 6. To visualize this, we can draw 10 cookies and cross out 4 to see that 6 remain.
Let's practice addition together. If we have 6 birds in a tree and 2 more birds join them, how many birds are there now? Write the equation: 6 + 2 = ?. Now, let's solve it together. Count the total: 6 plus 2 equals 8. So, we write 6 + 2 = 8. Can anyone explain how they counted the birds?
Now, let's try a subtraction problem. If there are 12 pencils and 5 are taken away, how many pencils are left? Write the equation: 12 - 5 = ?. Together, we can count down from 12, crossing out 5 pencils. We find that 12 minus 5 equals 7. So, we write 12 - 5 = 7. Who can tell me how they figured that out?
Now it's your turn! Solve the following problems on your own: 1) 7 + 5 = ? 2) 15 - 6 = ? 3) 9 + 4 = ? 4) 20 - 8 = ?. Remember to show your working clearly. Once you finish, check your answers with a partner and discuss any mistakes you might have made.
Answer: 7
When you add 3 and 4 together, the total is 7.
Answer: 7
Subtracting 3 from 10 leaves you with 7.
Answer: 8
You add 5 and 3 to get a total of 8 oranges.
Answer: 9
When you subtract 5 from 14, you are left with 9.
Answer: 8
The sum of 6 and 2 is 8.
Answer: 9
Subtracting 9 from 18 gives you 9.
Answer: 6
After eating 4 candies from 10, you have 6 left.
Answer: 7
After 5 balloons pop, you have 7 balloons remaining.