Input and Output

Start with a number you pick and write on the board. Then come up with a rule in your head and write the result on the board.

Now leave it to students to figure out what operation you performed to come up with your result.

You can adjust this mental math activity based on the level of your students. The rule you use can be very simple, such as basic addition or subtraction or it can be more complicated, such as raising a number to an exponent or a series of operations.

For example, let’s say you begin with the number 7 and you get these results for different levels of students.

• 7 yields the result 10 (You added 3.)
• 7 yields the result 2 (You subtracted 5.)
• 7 yields the result 49 (You multiplied by 7 or raised 7 to the 2nd power.)
• 7 yields the result 121 (You multiplied by 17 then added 2.)

Fast Multiplication Facts

Do the students in your class need review of their basic multiplication facts? You may not think of multiplication facts as mental math, but each time a student is asked for a fact, he or she has to go through the following steps:

1) What fact is my teacher asking for?
2) Do I remember that fact?
3) Student pauses for a ½ second.
4) The answer to that multiplication fact is ______. I think I know the answer (and I didn’t have to use a calculator or count with my fingers or toes!)
5) Teacher, the answer to 6 x 8 = 48. I got it right!

This fun game will give kids another way to practice their facts and make their ability to provide the answers to multiplication facts more automatically.

Divide your class into teams of three and give each team a deck of cards with the face cards removed.

Give each team a number to use as a factor. They will keep that factor until they go through their entire stack of cards.

Let’s say you give the first team the factor 7 to work with. Two players will play against each other and the third member of the team will keep a record so that everything is fair and square!

Player 1 turns over the 6 of diamonds. He or she multiplies 6 times the constant factor of 7 and gets the answer 42.

Player 2 turns over the 9 of hearts. He or she multiples 9 times the constant factor of 7 and gets the answer 63.

Since Player 2 had the largest product, he or she collects all four cards for that round.

In the event of a draw, which would happen if the players turned over the same number in different suits, they simply choose again. Whoever wins that round takes all 8 cards.

The rounds continue in this fashion until all the cards in the deck are used. The player in each team who collects the most cards wins.