Coin Perimeter 3 Act Task

This is a task that 2 of my second graders created and posted on our class blog. I use the kidblog app and website for my students to type about things we are learning, respond to one another’s posts, and share tasks that they have created with their devices during station time (we are a BYOT school).

Standards: 2OA4, 3MD8

ACT 1 

Part 1

Single penny

What do you notice? What questions do you have?

How many pennies tall is the stack of bills? Make an estimate. Also make an estimate that is too low and one that is too high.

Part 2


What do you notice? What questions do you have?

How many stacks will it take to go all the way around the bills? Make an estimate. Also make an estimate that is too low and one that is too high.




What do you notice? What do you wonder?

How many pennies are there total? Make an estimate. Also make an estimate that is too low and one that is too high.



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Flip the book: 3 Act Task

Standards 2NBT5, 2NBT7, 2NBT9


Watch the video.

What do you notice? What do you wonder?
Make an estimate. Write an estimate that is too high and one that is too low.



This is half of the dictionary.



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To learn from the best about 3 Act tasks see Dan Meyer’s blog

Other great sites of 3 Act Tasks are:

My students and I LOVE Estimation180 but I have to carefully select which estimations we do since some are over their heads (I teach 2nd grade). Since we are a BYOT school, my students and I have decided to create our own estimation tasks and take pictures, videos, etc. One student wanted to estimate how many counting bears were in a bag so they got in groups, grabbed bags, and started estimating. They, of course, had to do a high and low estimate first and then counted their bears to see if they were close. They took pictures and videoed themselves counting the answers. It was great.

This gave me the idea of creating a 3 Act task with a larger number of bears to encourage my students to add four 2 digit numbers (our upcoming skill).


Watch the video:

What do you notice? What do you wonder?

  • How many counting bears are there?  Estimate.
  • Write an estimate you know is too high.  Write an estimate you know is too low.

Act 2

IMG_0269 IMG_0270 IMG_0271

Act 3

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I Beat Subtraction With Regrouping

Oh, subtraction…how it can be a thorn in my side! This year subtraction has been a difficult battle for me. I have been an advocate for student invented strategies for years now and have used them in my classroom. I mainly used them for multiplication and long division when I taught third grade under GPS. Now I teach second so they are mastering addition and subtraction. Subtraction with regrouping is always a battle. In first grade they learn basic subtraction and therefore come to second knowing to count backwards. When they get to a problem like 32 – 27, most students (all but 2) just made it 37 – 22 and subtracted. They did this when writing numbers horizontally as well. The rest of my grade level teaches the traditional algorithm explicitly and that’s what the students learn. Through all of my research, I just couldn’t do it. Last year I started with strategies and then conformed to my peers and taught the algorithm…feeling pure guilt the whole time. This year I was determined to stick with it and prove that it works. Through lots of investigation with numbers and manipulatives my students were able to come up with 4 different ways to subtract that will work every single time and are efficient for those that understand them. Trying to get all 49 students that I teach to invent a strategy is unrealistic, but many students did. There were hard days where I wanted to give up. Days where they just went out to recess early and I prayed through tears (and a Twix) for direction. Days where I left uncertain if I was doing them wrong by not standing up and teaching the steps. On those days I would read my Van de Walle books and read the blogs of my math minded friends. I would pray and regroup my thoughts and start fresh the next day. Our curriculum guide for our county gave us 3 weeks to teach 2 digit addition and subtraction (yeah right)….I took 3 ½ months. I did our other skills along with it…we did measurement, coin recognition, graphing, etc, but would do at least 2 addition and subtraction problems every day. I made slides for each of the four strategies my students came up with and the whole class had to try each one a few times before deciding on the one or more than one strategy that they wanted to adopt as their own. One of the strategies was the traditional algorithm. Two students showed it to the class (one is a repeater and one is from China and learned it there). They were able to explain it with manipulatives, so it could be used. We called it the “old way” since it’s the way I did it in school and they think I’m old. I sent a letter home to parents explaining the importance of invented strategies and pleading to let their child use the strategy that made sense to them. I also sent a “how-to guide” for the 4 strategies we came up with in class so that parents could help their children with homework. We are finally taking our test this week. I’ve been testing in small groups and so far they have done a phenomenal job! I am so incredibly pleased. My low students are performing way beyond what I thought they could do. I am now so thankful that I stuck through the hard times and persevered. It was worth every stressful day to see my students to not just subtract with regrouping, but to subtract with UNDERSTANDING!

Student Invented Subtraction Strategies

Student Invented Subtraction Strategies

Student using counting up (Gordon's Way) on a test

Student using counting up (Gordon’s Way) on a test

Student using equal distance (Vincent & Michael's Way) on a test

Student using equal distance (Vincent & Michael’s Way) on a test

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My Name is Christy and I’m a Rule Follower.

I have always been a rule follower. I like rules. I thrive in structured environments. I’m not very organized, but I am very structured, if that makes sense. I think that’s why math always came easy to me. I could easily memorize and follow rules. It wasn’t until I was already a teacher and took some math courses for Professional Learning that my rule following math approach was tested. Once I began my Master’s Degree in K-8 Math Ed from the UGA campus in Griffin my math world was really shaken up. I was a pro at getting my third graders to master the art of carrying and borrowing. They knew the “alligator’s mouth” opened to the biggest number. They knew when multiplying multiples of ten to just count the zeros and stick them to the end. They even knew “Daddy, Mama, Sister, Brother” for divide, multiply, subtract, bring down with long division. My students did great on the CRCT…those that were like me and remembered all the rules that is, which most could do. Was there conceptual understanding going on? A little. I broke out base 10 blocks and thoroughly explained how the algorithms worked. Have I mentioned I’m very detail oriented? Could my kids explain why the steps they were doing made sense mathematically? Probably not. Honestly I don’t know, because I never asked them, “Why?”. Then, during my Master’s program my teacher kept asking me why and wouldn’t give me the algorithm or let me use the traditional one. WHAT?!? I need the rules so I can follow them! What do you mean I’m supposed to think for myself? How is there more than one way to subtract other than crossing out and borrowing/trading? You DON’T have to carry a 1??? Mind blown. I read articles about student invented strategies. I read in Van de Walle’s books about it. I didn’t believe it. I decided to do my research paper with that as my thesis to see if students could even come up with anything that remotely worked. I learned a valuable lesson while letting my kids explore, experience hardships, and encouraging them to push forward all while fighting really hard (sometimes only through prayer) to just not give them the algorithm. I learned kids are smarter than we give them credit for. Yes, they need guidance and needed help organizing their thinking, but they came up with ways to do all 4 operations in ways that I still use. Anytime you learn anything and grow, you do it through a little hardship. My son is 8 months old. Everything he’s learning requires a lot of falling over before it’s mastered. Even knowing this, it’s an internal battle every year when it comes to subtracting with regrouping to not just show them the algorithm…especially now that I’m in second grade and they have little to no knowledge of it, but I’m fighting on and my kids are absolutely amazing me. More on my subtraction adventure later. I’m still a rule follower. I just make up my own rules to follow at times. Try it. Your kids will AMAZE you.

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