Explain your thinking

Many of our Math problems in Grade Three are followed by the statement: Explain your thinking. We call it "EYT" for short.  

When we ask students to explain their thinking, we're asking them to tell us how they know they're right. We're not asking them to explain the steps to how they solved the problem.

Wait. 
What? 

I know, you're probably thinking how can a student describe how they know they're right without explaining steps?  It's a really, really fine line.  

We're asking students to tell us about the strategies they used WITHOUT telling us how to use those strategies. Have a look at this very basic example below: 

Patti has 12 stickers. 
Paul has 36 stickers. 
How many more stickers does Paul have than Patti?
Explain your thinking.

A student who "gets" how to EYT would explain that they subtracted 12 from 36 to find how many more stickers Paul has. Then,they might tell readers that they flipped the question and added 24+12 to make sure their calculations were correct.  

What they shouldn't do is write the instructions for HOW to subtract. For example: First, I subtracted the 2 from 6 in the ones column. Then I wrote down 4. Next, I subtracted the 1 from the 2 in the tens column...

This tends to be a common mistake early on and only lots and lots of practice helps students identify the difference between explaining their thinking and writing instructions.