The Calendar

In this short guide you will be able to preview the segment. You’ll also get some great ideas for in-class activities after watching the video with your students.

Here is a creative and fun in-class activity for after watching the video…

Practice and play
with students in class:


✅   A printed page of a monthly calendar (any month or year)
✅ Colored marker


The Game:

✅ Download the calendar page from the link below and give one to each student.


✅  Split the class into teams of 2 and let them play the game: one will be the “mentalist” and the other students will mark the square around 9 dates on the printed calendar. When finished, the mentalist will find the answer while the other students will add the dates on a calculator. When the mentalist gets the correct sum, they will switch parts.


✅ Encourage the students to practice their multiplications and share the excitement with family members and friends.


The Calendar - a sample page to download

Why it


Let’s take this calendar page (August 2015) as an example. The red frame is covering 9 dates.

Calendar 1


Let A (in our example, #10) be the central number of the 3×3 square.

Calendar 2


Now, look at the date in the center. The day before is A-1, the day after is A+1

Calendar 3


The date above (exactly a week earlier) is A-7 and the date below is A+7

Calendar 4


As you can notice, the pairs have opposite numbers that cancel each other out…

Calendar 5


…and the same thing happens here, with the last pair.

Calendar 6


All these pairs add up to 8A, and with the central number add up to 9A.

Calendar 7


The sum of all 9 dates within the square will always be 9xA. (A is the center number in the square)

After watching the Teacher’s Guide it is time to share “The Calendar” with your students in class.

Please note: you must have a
password to view the segment.

We would love to hear from you. Your thoughts will help us develop and produce future videos. Please let us know how it worked in class, your students’ reactions, and the level of difficulty.

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