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Sunday, October 27, 2013

Adding and Subtracting Decimals Activities & Freebies!

I've mentioned before that I have the same group of students this year that I had last year, so I am having to recreate the wheel quite a bit this year, as the standards overlap a bit.  One of those overlaps was adding and subtracting decimals.  We spent a lot of time on it last year, and I used all the decimal resources that I had already created with this group last year.  We didn't need to spend much time on it this year since it was more of a review, but I wanted to make it fun.  And fun, it was!  Read on to find out all the fun activities we did, including some freebies for you!

We began with estimating sums and differences of decimals, which the students actually really enjoy doing (and it also happened to be the day I was being observed by the principal).  We used a foldable from 4mula Fun (love her foldable pack) that I adapted from one of her units to explain two different types of estimating decimals.  On the inside, we did an example together, and on the flap, they had to come up with their own scenarios when we might use the different types of estimating in real life.  They did a great job adding in that element!  After we did the first type of estimating (front end estimation), I gave them each a task card that I had created for estimating sums and differences.  They had to use front end estimation to find the answer.

Estimating Sums and Differences of Decimals Task Cards
Then, they shared their card with a partner and their strategy for solving the problem. We moved on to the next strategy for estimating.  After we did that, they passed their cards down 4 people (so that they wouldn't be doing the one that their partner had just shared with them, and so that they could get a different type of card, since there were three different types of cards in the set) and completed their card using a different type of estimating.  Again, they shared their card and solution with a partner. You can see in the picture to the right that we also used our HALLOWEEN adding and subtracting decimals task cards to practice later!  I really wanted to make a point of explaining how we used this set of task cards because it was very, very effective, but a different way than we usually think about using task cards.  Each child only ended up doing a few, but they loved them!

After that, we did a flow map together to make an adding and subtracting decimals anchor chart.
Adding and Subtracting Decimals Anchor Chart
They copied it into their math notebook and then they had to make a flow map to show the same problem, but with subtraction.  They were all amazed that something that *seems* so simple actually took 5 steps to process!

The next day we started my FAVORITE part of our decimals study (and the part that is totally free for you)...Candy Conundrum!

I got the idea as I was sorting through ads last Sunday trying to figure out where it would be cheapest for us to go and buy Halloween candy.  I decided I would let the students figure it out for me, and Candy Conundrum was born!  And let me tell you, they beyond loved this activity.

All I had to do was print out extra ads (which you can find here) and make the cards (which you can download for FREE here.)  I wrote the cards so that they are candy specific, but not Halloween specific, so you can use them pretty much any time there are ads with candy!  I designed the cards so that they would be practicing estimating sums and differences as well as adding and subtracting decimals.

  I did VERY little explaining other than asking the kids if they ever look through the Sunday ads and compare prices.  I got a lot of blank stares, so I told them that today they were going to do just that, and I sent the kids off to do their work. The cards explain themselves.  I was amazed at how well the students did and how engaged they were the entire time!

This is, again, a different take on using task cards.  There are only 4 task cards in this bunch, but they are successive, so you have to do card #1 to be able to do card #2. Each pair of students started out with Task Card #1.  When they finished Task #1, I looked over their work and gave them Task #2, then Task #3, etc.  They really enjoyed this, and they were always excited to see what the next card would require them to do.

An overview of all four tasks the kids completed.  I also printed out the coupons from online sites and wrote VOID over the barcodes to keep it legal!
Student work after completing task #1

Y'all, I did NOT pose the picture above with the two kids comparing.  There was a hilarious moment here when the kids realized that you get a free gift card when you buy two, therefore making the slightly more expensive candy "cheaper" when, and only when, you buy two.  It was so fun to watch them make the connections and get more and more excited.  Finally, they slammed down the ads and said, "BAM!  How's THAT for finding the best deal!?"  Later, they found a Target coupon for the same candy, and I thought they were going to explode with excitement.  It cracked me right up.

Above is a look at an almost finished project (without the coupon task done).  You can see that I didn't give them any type of recording sheet because I have really been focusing on getting them to show their work in an organized manner.  This was the "proof" portion of their math notebook for adding and subtracting decimals.

I also created three more similar sets of these scenarios, and each student chose one to do at home throughout the week.  They haven't turned them in yet, but I got two emails from different parents telling me how much fun their students were having shopping for deals!  Then, this morning, a parent emailed me and told me that her child had spent an hour comparison shopping the ads in this morning's paper.  I consider that a success!

  You can download the three additional scenario cards for FREE HERE.  They would be great for the classroom, too.  Again, you just need ads and the cards.
An example of a four part task for adding and subtracting decimals!
(Fonts from KG Fonts and Papers from Mr. Magician
After this, they completed the adding and subtracting Halloween task cards ($2.75) that I showed in the picture above.  I gave them 30 minutes to work through as many as they could and graded only what they finished.  If they got at least 90% of the cards they attempted correct, they didn't have to do anymore.  If they got fewer than 89% correct, they had to do some more of the cards.  It was a great little assessment.

On Friday, they did this fun freebie activity called "Rent For a Day."  Each student got a copy of the rent prices for the day and kept track of their spending.  They really enjoyed it, and some have even asked to keep doing it next week.  It would be a great way to review decimals if you pulled this out once or twice a quarter!

I didn't want to give them a formal assessment for this since I had so much evidence of their understanding.  I decided that they would complete an error analysis activity for adding and subtracting decimals instead.  I blogged about using error analysis HERE, and you can purchase my error analysis packs, including this one ($2) HERE.  I highly, highly recommend using error analysis in some way (even coming up with your own examples) in your classroom.  The benefits are amazing.

Okay, I think that's it!  We are beginning dividing decimals next week, and I plan to have them figure out price-per-piece of candy and some nutritional information in honor of Halloween.  That should also be great fun! Have a great Halloween week, and HANG IN THERE, because I know it's going to be a long one! :)


  1. You are amazing! What a fun set of activities. On the candy task cards you refer to a stack of coupons. Did you just gather candy coupons and give each group a set, regardless of whether that type of candy was in the ad? Thanks

    1. Hi Jen! I printed off coupons from and from I just chose candy coupons, but left it up to them to match it up to an item. There were a LOT that matched up, though.

    2. Great. Thank you. This is a wonderful way to make the math skill applicable to a real life situation.

  2. Thank you so much for the freebies. We have just completed our unit on addition and subtraction of decimals, but can't wait to use for next year.

  3. We just started this today as a review in our class - THANK YOU! This is perfect for Halloween when it takes a magician to keep kids' attention. My class will absolutely love this.

  4. I am in LOVE with all of your hard work that you have done on your Interactive Notebooks! Just pinned this post to my Flippables and Interactive Notebooks board and hope that you get a ton of views. Love how you used so many flippables and interactive activities to keep your students engaged and interested in their learning while connecting it to real life.

    Jennifer Smith-Sloane

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  7. Love this project. I will definitely be doing this next year. Thank you for sharing!


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