S17: Blog 2: Decimals in the real world
- Emily Johnson
- Jan 15, 2017
- 4 min read
One of the most important things, I think, that we as teachers can do when we plan lessons for our students is to find ways to connect what we’re teaching them to the real world. This isn’t always easy to do in math. However, as we’ve been working through a unit on adding and subtracting decimals, I’ve found this goal more attainable than usual.
This week we were finally at the point in the unit where students would be using various strategies to add and subtract decimals. We spent Monday exploring how to do so using base 10 block manipulatives and quick pictures. Another resident and I were then in charge of planning the next day’s lesson, where students would be using place value (AKA the traditional algorithm) to add and subtract decimals. I knew that many of our students were ready for this leap from the concrete to the abstract because many of them had already demonstrated their ability to use the traditional algorithm. They were often excited to show me or my CT that they could “do it like this” rather than spend more time drawing the pictures or using the base 10 blocks.
Because I felt that most of my students would quickly pick up the traditional algorithm, if they hadn’t already, I knew that I wanted Tuesday’s lesson to primarily consist of an engaging, real-world activity that would allow them to apply adding and subtracting decimals. This led Sara and I to come up with the idea of providing advertisements from different grocery stores (Aldi, Publix, and Save-a-lot) to our students, along with a certain amount of money they would be able to “spend.” We also created a print-out for them that allowed them to keep track of what they were buying and how much it would cost. Our students would be adding decimals as they kept track of the amount of money they were spending on the items they chose to buy. They would be subtracting decimals when they subtracted the money they had spent from the “budget” they had been given, ensuring that they did not go over budget.
I also created a Classflow question set that students would complete independently after the activity, if time allowed. These questions were structured like questions would be on their upcoming unit test and were meant to identify students who were showing mastery of adding and subtracting decimals, as well as identify students who were going to need a little extra help. While I did that, Sara used her technology skills to find a website that allowed us to put our faces onto the “money” (paper bills) that we would be giving to our students for the activity.
As it happened, due to responsibilities in science during our two morning math classes, I taught the lesson Sara and I had planned to the last class of the day, while my CT taught it to our morning classes and Sara taught it to her homeroom early in the afternoon. One of the things I like best about teaching the same things four times a day is that you’re able to make changes to the lesson from one class to the next, based upon what you see. For example, by the last class of the day we were no longer giving out the money to use as a manipulative, because it was more of a distraction than a useful tool.
When the three of us, me, Sara, and my CT, had the chance to talk about the lesson at the end of the day we all had the feeling that we had met our learning objectives for the day. From the observations we had made across the four classes, it appeared that our students were accurately adding and subtracting decimals. We also discussed the high level of engagement that we had seen throughout the day. This we felt was related to the real-world nature of the activity. Math can often seem so abstract but this was something that our students see and do often as they go to the grocery store or shop other places.
FEAPS:
1c: Designs instruction for students to achieve mastery
3a: Delivers engaging and challenging lessons
3e: Relates and integrates the subject matter with other disciplines and/or life experiences
5g: Engages in ongoing reflective practice
6d: Maintains positive and productive relationships with colleagues
Evidence:
Picture of day’s EQ and objectives
Picture of question set
Picture of materials
Picture of students working
Lesson plan
Adding & Subtracting Using Place Value
Standard:
MAFS.5.NBT.2.7 - add, subtract, multiply, and divide decimals to hundredths, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
Objective:
We are learning how to use place value in order to add and subtract decimals.
EQ:
How can we use place value to find sums and differences of decimals?
Criteria:
We will be able to use place value to add decimals up to the hundredths place
We will be able to use place value to subtract decimals up to the hundredths place
Materials:
Promethean board
Store ads
Fake money
Grocery List worksheet
Classflow
Opening:
Make connection between place value and previous day’s use of base 10 blocks to explore addition and subtraction
Show how to add and subtract using place value; when regrouping make the connection to the base 10 blocks
Connection can also be made to similarity between adding and subtracting whole numbers and adding and subtracting decimals
Discuss how we most often see decimals in the real world when we’re shopping somewhere like a grocery store
Core:
Have students practice adding and subtracting decimals by giving them a certain amount of money to spend and having them “shop” for food and other household items for the week
Ads will be printed out from local grocery stores and given to students
Students will work with a partner to complete a budget sheet, where they list each item, it’s individual cost, and then the total cost of their shopping
Students will also need to subtract to show how much money they have left over
Partners will then switch with another team to check each other’s work
Closure:
Classflow practice problems similar to test questions
This can be used to assess which students demonstrate understanding of the concept and which students need to be pulled into a reteach group before their test on Friday
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