Whole Numbers Estimation: Real World Math Freebie

Math is a subject that I love to teach. I was a math nerd when I was in school. It just made sense to me and I could usually find the "right" answer. I also enjoyed problem solving and would push myself until I got it. There's just something about math that never makes me want to give up. As a teacher, I have always wanted to make math a "real-world" subject. I mean I always want to be able to answer "Why am I learning this?" when I'm teaching students. (My 4th and 5th graders rarely ask that question, maybe because most of them enjoy math, but aren't they lucky that I always want to make the real-world connection for them?) Now, I will admit, I spend way too much time stressing myself out about this, especially when it is an objective where I am the one saying "Why the heck do my kids need to know this?!?" And sometimes, I just have to move on with my life and just teach the concept at the highest level possible without addressing the "why we need to know this" question. 

Rounding and estimation are two topics that I now introduce with a "real-world" experience. This year, I wanted students to round larger numbers and estimate a total. I scoured the internet for good catalogs to use. Lego catalogs would be really cool if you had enough for the whole class. (I signed up for their mailing list, but plan to call and ask them to send me 25 of one catalog for future lessons). I asked parents for any suggestions--I really wanted the activity to be fun for the kids and for the catalog to contain things that they would enjoy shopping for, and I just didn't want to go the clip-art catalog route yet. FAO Schwartz was the perfect answer for my needs. 

For the lesson, students are guided through a number of "rounds" that have different constraints. In round one, we are just introducing rounding and estimation. Students: 1) have $1000 to spend and must buy three items, 2) have $1000 to spend and can buy as many items as they want, and 3) have $1500 to spend and can buy as many items as they want. They calculated the estimated amount and exact amount by hand and then checked it with a calculator. (These directions are all provided on the student handout in a chart format. After each part of round 1, I am sure to ask students to discuss the strategies they used for estimating. One of my students shared that they were looking for combinations of numbers--they chose an item that would round to 100 then they chose two items together that would round to 200 (like a $160 item and a $40 item). As I walked around and helped them fill out their charts, I asked how they were choosing their items. In the first rounds, of course, students are looking for things they want in the catalog, but by the end, they are challenged by the criteria to consider the costs more.  

My favorite part of the lesson (which spanned a few days) was when students were challenged in Round 2 to get as close to $1500 as possible with only 5 items. I did the challenge with them and many strategies came about that provided for interesting math discussions. For example, I was $4 away from $1500. I challenged them to see who could get closer than I did. Then, I started trying to figure out how I could get closer. Well, if one of my items cost $169 and I needed $4 more, then I needed to look for items that cost $173. I took my list of items and made added $4 to each one to see what exact cost I should be looking for. We loved this so much, it hit me that it would have been an AWESOME, engaging way to practice addition skills without students actually realizing it. 

Click here to get your free download of the FAO Schwartz Shopping Catalog and here for the student worksheets/guide I used for my lessons. 

In 5th grade, rounding decimals is huge, so I like to use a grocery store advertisement and follow a similar process as I did with the whole numbers estimation lesson. (You might want to go through the ad and change some of the prices to make the rounding task more challenging).  

Happy math teaching!