Question

Which strategy is used here to subtract $2$ from $11$ ?

• A. Make an $11$
• B. Make a $10$
• C. Make a $9$
• D. Make a $1$

Answer 1

The correct option is B Make a $10$

Say: Let's read the question and observe the image.

Ask:
$\bullet$ What do we have to do here?
Ans: We need to identify the strategy used to solve the equation.
$\bullet$ By looking at the given image, what can you understand?
Ans: $2$ has to be subtracted from $11,$ i.e., $11–2.$
$\bullet$ How do we do this?
Ans: (i) We find out what number needs to be subtracted from the greater number to make it $10.$ Here, we need to subtract $1$ from $11$ to make it a $10.$
(ii) Then we split the smaller number into that number. Here, $2$ is split to $1$ and $1.$
(iii) After which, we subtract the remaining part of the number from $10$ to get the difference. Here, $1$ is the remaining number, which is subtracted from $10$ to get the difference as $9$.
$\bullet$ So, based on the given options, what strategy has been used to solve the equation?
Ans: Make a $10$

Hence, Option C is correct.

WB: Use the whiteboard to write the equation and find the total using the make a ten strategy as shown and explain the steps.


Probing Question:
Can we solve the same equation using the “make a ten” strategy by breaking down $11$ into $9$ and $2$ ? If not, why?
A. No, because if we break $11$ into $9$ and $2,2$ and $2,$ i.e., $2–2,$ gives us $0$ and $9$ will be remaining. We have not made a $10.$