Lesson+1


 * Lesson 1: Would you recognize subtraction if it looked you in the eye? **

media type="file" key="SubtractionMissionLesson1.mp3" width="240" height="20" (Click here to listen to the text of this lesson.)

Would you recognize subtraction if it looked you in the eye? For every special agent it is a matter of life and death to recognize the mission’s crucial element: subtraction. You need to be able to identify subtraction, no matter the circumstances, even “with your eyes wide shut” as Dr. Seuss would say. Therefore, make sure you don’t underestimate this task.



** Review: **

Do you remember how to differentiate between the following number problems?

** Addition: ** I have a pair of sunglasses; my friend gives me another pair. Now I have two pairs.

1 + 1 = 2

** Subtraction: ** I have a pair of sunglasses and an enemy steals them /takes them away from me. Now have no sunglasses.

1 – 1 = 0

** Multiplication: ** I have a pair of sunglasses. Two special agents are assigned to join my mission and we have to figure out how many individual glasses we have. We have six individual glasses.

2 x 3 = 6



Write down the subtraction number sentence in your Mission Notebook and circle the subtraction symbol. Then write three more subtraction problems with your own numbers. Circle again the subtraction symbol.

Can you explain in your own words how you recognize subtraction? Write it into your Mission Notebook.

** Conclusion: ** You have completed an important first step within Subtraction Mission (Im)Possible. Knowing what subtraction looks like will ensure that you easily recognize it when you come across such a problem and apply the right methods in dealing with it. You wouldn’t want to end up applying the subtraction process to an addition problem, right?



** Assessment: **

Please complete the following assessment to earn your first star in your special agent badge.

Which of the following are subtraction problems? Write them in your Mission Notebook.

(a) 25 – 13 = (b) 38 + 22 = (c) 3 x 2 = (d) 4 x 2 = (e) 48 – 25 = (f) 21 + 56 = (g) 63 + 12 = (h) 72 – 68 = (i) 2 x 3 = (j) 27 – 9 =

Go to the **Lesson Exercise Keys** page. Open **Exercise 1** and compare your answers. If you have all answers correct, add the first star to your badge in the Mission Notebook. If you need more practice, please repeat the lesson tomorrow before you work on Lesson 2.

Click here to go to Lesson 2.