Okay. My third-graders are learning how to round to the nearest hundred. Wait. Let me rephrase that. My third-graders are supposed to be learning how to round to the nearest hundred. Two Mondays ago, we studied rounding to the nearest 10. We used a variety of hands-on strategies to accomplish this goal, and it was mastered fairly quickly by all students. (That isn’t as impressive as it might be, by the way; I’ve only got three third-graders.) This past Monday, we started rounding to the nearest hundred. They did fine. For the first few lessons. I swear. They knew how to round to the nearest hundred when they left on Monday. And they knew how to round to the nearest hundred when they left on Tuesday. But when they came back on Wednesday? It was GONE. As if we had never studied rounding before. Today, it was even worse than that. Today, it was as if they had never even been to school before. They didn’t know how to put their names on their papers. They didn’t know which desk belonged to who. And they DID NOT know how to round to the nearest hundred. I kept my patience … for a while. I showed them how to narrow their choices down to two possibilities – the two multiples of hundred that are nearest to the number in question. When they didn’t seem to remember this concept, I made it even easier. “The two choices,” I said, “are 600 and 700.” “I know!” shouted Student A. “5,000!” Just as Student B shouted, “27!” “Guys,” I said, bewildered, “the answer is either 600 or 700. Those are the only two choices. The number you say either needs to be 600 or 700. So no other answer has even a chance of being correct. So … which is it? 600 or 700?” “94!” shouted Student B. “400!” shouted Student A. Luckily the students left for lunch about that time, saving me from pulling out chunks of my own hair in frustration. They returned half an hour later, refreshed and ready to tackle rounding anew. Yeah. After fifteen minutes of rounding torture, I decided I’d better return to safer waters. I put a few two-digit numbers on the board and asked students to round them to the nearest 10. So imagine my surprise when the answers ranged in length from a single digit to six. Defeated, I handed them their homework papers. “What do we do?” Student B. asked. “Circle the number that is in the hundreds place,” I instructed. “That way, when you come back on Monday, we’ll be ready for rounding.” Student B. wrinkled his brow, looked me in the eye, and asked, “What’s rounding?” You know what? I’m not sure even I know the answer to that question anymore. Does anyone have any great strategies for getting rounding to stick?