# I’m Thinking of a Number

Choose a number between 1-100 but don’t tell your class what the number is. Now they must ask you questions to determine what the number is. But here is the catch…if they ask you a […]

# Happy Waitress, Mad Waitress – Tipping a Waitress With Mental Math

Split your classroom up into teams. Each team will have a restaurant patron and a waitress (or waiter). Give each team a slip showing what they had for dinner and the sum of what they owe. Make these different slips for every team.

# Karl’s Sum: Even famous mathematicians don’t always behave!

One day when students in Karl’s class were really noisy and displaying bad classroom behavior, the teacher got very upset. He gave them a problem to solve. He asked them to find the sum of all the counting numbers from 1 to 100: 1 + 2 + 3 + 4…… + 99 + 100 =

# Let’s Find the 10s {FREE}

You can do this activity with your students at the board or on worksheets.

Provide them with a really long horizontal sum. Something like this:

3 + 11 + 7 + 5 + 5 + 4 + 9 + 1 + 2 + 13 + 8 =

The idea here is to group pairs of numbers into tens or multiples of ten so that they can quickly and easily find the sum using mental math.

# Mental Stretch

Here’s a fun game that you can play with the students in your classroom to get their mental juices going! Begin with a simple whole number like 5. Then start giving the students operations that they should perform in their heads. Use a variety of all four operations and make sure the directions you give will yield whole numbers.