Revisiting the Introductory Challenge

It seems like Jessica had to have lots and lots of practice in order to become a “math loser.”  And yet she was just as smart as Sam and worked just as hard (or harder) at the things she really enjoyed. Imagine how much more math she could have learned, and maybe even come to like, without all of the pointless practice.

It’s not that practice is bad. It’s essential. It’s just that bad practice is bad, and for Jessica the endless round of flash cards year after year didn’t help. It actually made things worse for her.

If someone had helped her develop number sense instead, she would have spent her time a lot more profitably. She’d know more math now, as an adult. And she might even feel more competent as a person.

But what about number sense? In the activity, there’s a definition that bears repeating:

Number sense is knowing how a number can be taken apart and put back together, and then using that knowledge to solve math problems.

How many ways can you think of to “take apart” the number 8? Remember—you can use any operation and any number of numbers (positive and negative).

In truth, there are an infinite number of ways.

And how about 9? Give 6 or 7 answers!

How you put them back together depends on the problem you are trying to solve.

So let’s look at 8 times 9—which is 72.  But let’s pretend we don’t know the answer: just like many students. How do we get to the answer from things we probably do know (like 2 times 3 is 6)?  Here’s the hint:

2 x 2 x 2 x 3 x 3 … then what do you do? (Answers vary depending on what you think will make computation easier.)