Tag Archives: money

Unit Cost and Actual Shopping

I previously shared that grocery shopping has a lot of tasks that are overlooked. One is working with unit costs. There are two math tasks related to unit cost, interpreting what a unit cost is and computing the total cost for buying multiple items.

When I take a student into a grocery store to work on unit costs, where is what I do. I start with a pack of items (photo on the left) and ask the student to compute the cost for 1 item, in this case, “what is the price for the pack of chew sticks, how many in a pack, how much for 1 chewstick?” Then I prompt the student to compute the total if he buys 3 packs. This allows the student to differentiate between the two tasks. The cost per items is easier to grasp and then is followed with the same prompts for a jar of sauce (below right).

I then have the student compare unit costs for the large vs the small jars and ask, “do you want to pay $4.99 per ounce or $5.99 per ounce.” This language is more accessible than “which is a better deal?” You can work towards that language eventually.

These tasks can be previewed at school with a mock grocery store. The price labels can be created on the computer.

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Counting Money – Jamboard

If you have a student who is learning to count money, here is a virtual set up to do so. I suggest having the student do a test run by moving coins into a box and bills into a box. It is easy to duplicate each item by clicking on the item to duplicate it.

If it works, you can insert images of items to purchase. Note, I start with just pennies or just $1 bills and incrementally add additional currency. I also present items to purchase that are of interest to the student – the image below was used with a student who loves Minecraft.

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Counting Money at the Store

The way a student counts money in school on a school desk or table (top photo) is the way he or she will attempt count at the register as seen in the 2nd photo in which the student pulled all bills from his wallet then counted, with some bills folded. (Bonus if you can identify the woman in the photo!!!)

In the top photo (below) I had the student pull bills out from his wallet, with the bills unfolded and in order in his wallet (you can see he pulled a $20 bill first). In the next photo you can see that he is counting out the bills from the wallet as he did in practice.

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Intro to Reading Scatterplots – Used Mustangs

One step in reading and analyzing scatterplots is simply identifying what the dots on the graph represent. If students do not understand the dots (including the position) how can they analyze. An approach I have used is start by having students create their own scatterplot for mileage and price of used cars they shop for on Carmax.com. This allows them experience the scatterplot from a data and context point of view.

Then I present the scatterplot of used Ford Mustangs on a Jamboard (image above) with ads for two used Mustangs along with a cutout of each car. The goal is to help the students understand the reasoning behind the position of each dot.

First, I take the cutout of the first car and “drive it” along the x-axis (top 3 photos in gallery below). This helps them understand the horizontal axis placement. Then I move the car up to the appropriate price (bottom row left). Finally, I replace the car cutout with the bigger blue dot that was placed by the ad with the car. We then discuss that a dot can be used to represent that car and the location on the scatterplot is based on the two values in the ordered pair (which can be typed into the ( , ) in the Jamboard next to each car.

The same steps are used for the other Mustang (see it “driving” along the x-axis below).

The next step would be to identify additional points on the scatterplot. I then revisit driving the cars and show that driving the car more miles results in a lower price and driving the car less miles results in a higher price. Finally, we discuss that this is a general trend but that it is not always true for each car. I highlight a couple points where one of the cars has more miles and a higher price (below). This leads into a discussion about additional factors influencing price.

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Intro to Systems of Equations: Camry vs Mustang Depreciation

The scatterplot above is an approach I use to introduce systems of equations. Here is the process I use. (Note: I have found that students like math associated with buying a car – relevant, real life application for them.)

  • In my class, students would have seen a scatterplot with mileage and price for a single car. I explain that we will now compare two cars.
  • To review, in a do now or initiation at the start of class I would have one group generate a scatterplot for the Toyota Camry data and the other groups, Mustang (Excel sheet for all of this note: this data is old). Then they would share with each other
  • We would revisit the relationship shown and revisit the idea of depreciation.
  • I show a Camry and Mustang and ask two questions: Which car do you think costs more brand new? Which do you think depreciates faster and why?
  • Then I show them the scatterplot above and ask which car has higher dots at the far left? Explain what this means (Mustangs start off with a higher price). Then I ask about the dots at the far right.
  • The students are then asked to estimate when the cars have approximately the same value.
  • Then I present scatterplot below, with lines of best fit (trend lines) and they are asked the same question. We estimate the specific mileage and price and write as an ordered pair.
  • Finally, I explain that this is known as a system of equations and the ordered pair is the THE solution. The entire unit will focus on finding an ordered pair as a solution.

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Monthly Budget Project

The images shown are excerpts from the latest iteration of a budget project I have used for years. The content addressed in this project can be used as stand alone activities and are relevant real life examples for our students. Even the younger students could benefit, e.g., learning addition by shopping for items online and recording the prices (for older students throw in computing tax). These topics are especially useful for multiplication word problems, rate, single variable equations, and linear functions (slope being rate of change such as car payment per month).

Here is an overview. You graduate from high school and are living on your own. You have a job, but your car is getting old. You need to figure out how to save for a down payment in your budget and for when you must pay a car payment and insurance. (You will have to get your OWN insurance.)

The image below shows the table for all monthly expenses.

The students have imbedded activities such as

  • estimating monthly food costs by estimating cost for meals for a single day
  • shopping for disposable household items
  • shopping for car insurance based on the car they shop for (more on that at the end) NOTE: they do not share personal information other than a school email address (or my email address) to receive the quote
  • searching for a job with a hourly pay and estimate after tax income

They shop for a car last as the idea is they need to save up for a down payment. The amount they can save is based on how much money is left over after paying all other bills. How much they save will be converted to how much they can spend on a car payment and monthly insurance payment.

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Multiplication with Integers: a Meaning Making Approach

I previously tackled the difference between the ” – ” symbol used to represent a negative and a subtraction problem. This post gets into multliplication through the context of buying a Wendy’s frosty.

One comment to preface what is presented here. Negative numbers are abstract and challenging for many students. Multiplying by negatives is even more so. The approach presented here for multiplying gets a little complex, which is inherent to the topic. In other words, this is an involved process as “there is no royal road to geometry.” What I present here is a path I develop over time, as seen in the sequence below.

First, review of a couple building blocks. Multiplication can be represented at groups of items. 2 x 3 can be represented as 2 groups of 3 $1bills, e.g., you bought 2 Frosties for $3 each.

Negative in terms of money can mean you owe money. Hence, -3 means you owe $3, e.g., you order a frosty and owe $3.

If you change your mind and cancel the frosty, the $3 you owe is cancelled and you get your money back. +$3.

If you order 2 frosties, you owe $3 and another $3, which is -3 + -3. (You owe $6 or -6.)

Cancel those two frosties and you get your money back. -(-6) is now +6

2 x -3 means you means you have 2 negative 3s – repeated addition, or -3 + -3.

If you ordered the 2 frosties and owe $6 then cancel, you get your $6 back or +6.

In mathy terms, cancelling the 2 x -3 is written as -(2 x -3) or -2 x -3.

The – for the -2 can be held out front to focus on 2 orders of frosties or 2 x -3. That was covered previously. Then the extra negative cancels that order so you get your money back. And so you have multiplying two negatives!

All images were generated on this jamboard.

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Scientific Notation – an Introduction

In a previous post I asked readers to identify a math topic that they wanted help unpacking. Scientific Notation was cited. Here is my approach to unpacking this topic.

My first step in presenting a new topic is meaning making. For scientific notation, the underlying idea is NOTATION – “the act, process, method, or an instance of representing by a system or set of marks, signs, figures, or characters.” We can represent numbers in different ways, one of which is scientific notation. This is useful to represent very large or very small numbers (as happens in science). It is useful because in lieu of writing out a bunch digits, the power of 10 can be used as a shortcut. In the image above you see that 4.5 x 104 has two parts, the decimal and the 10s.

Before I get into these big or small numbers, I address the concept of notation because that word is in the topic. To introduce a concept, I typically start with a related topic that is relevant for students. In this case it is money. To mirror the two parts of scientific notation, I list the bills and how many of each. In the left image below, I show both parts and pair combinations that are the same value (a single $10 bill and ten $1 bills). I then show how I can convert a single $10 bill by dividing by 10 and then multiplying the number of bills by 10 (middle image). This previews the steps used in scientific notation. Then (right image) I show the same approach for dollars and cents (which previews decimals). Note: to help flesh out the dollars and cents I would first use the linked Jamboard.

The image below left keeps the concept of money, but the images are faded. The students are still working with money and how many but now with numbers only. The middle image introduces decimals, but the same steps are used (divide by 10 and multiply by 10).

Finally, the matched pairs shown in the previous handout pages (images above) are presented with an explanation of the parts of scientific notation (below left). I explain the idea of scientific notation as a special way to write numbers, list the two parts, and then I show examples by circling the ones in each pair (bottom left) that fit the criteria. Then they identify numbers that are written in scientific notation (below right).

Following this introduction lesson, I would explain the applications (linked above) and go into more detail on how to rewrite the number in scientific notation.

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Worksheet Websites I Use and Recommend

The following are screen shots of online math worksheet websites I use. The variety and the options in the criteria you select for your worksheets for some of these sites allows for differentiation in the classroom.

 

I will start with my favorite site, Math-Aids.com. This site allows for dynamic selection of criteria for each handout (see 2nd photo below) such as choosing the types of coins in problems for counting out the total value. The coin images are outstanding! It also offers content up to Calculus.

 

 

Super Teacher Worksheets is often used elementary schools. It offers content in science and language arts as well. It requires a $25 annual subscription which I easily find to be worthwhile.

 

 

Common Core Sheets is very useful site if you want to find handouts for specific standards by grade level (see 2nd photo below). It offers multiple versions of each handout.

 

 

 

Dads Worksheets provides a large bank of worksheets – multiple versions of each worksheet.

 

 

Math Worksheets 4 Kids offers multiple versions of each worksheet and content in science and language arts. There are many worksheets that provide unique support in how the work is presented, e.g. the Ratio Slope worksheet shown in the 2nd photo below.

 

Visual Fractions – title speaks for itself.

 

Worksheet Works is my 2nd favorite. It offers options in the criteria you choose, e.g. difficulty level (2nd photo below). They also offer unique types of handouts such as a maze with math problems to solve to find the path (2nd photo).

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Shopping at the Grocery Store

There are numerous hidden tasks that we undertake while at the grocery store. We process them so quickly or subconsciously that we are not aware of these steps.

As a result, we may overlook these steps while educating students on life skills such as grocery shopping. Subsequently, these steps may not be part of the programming or teaching at school and therefore generalization is left for another day. Yet, the purpose of IDEA is, in essence, preparing students for life, including “independent living.”

To address this, we can take a task analysis approach in which we break down the act of shopping at a grocery store into a sequence of discrete steps or tasks (see excerpt of the task analysis document below).

Step 1 is to administer a baseline pretest during which we start with no prompting to determine if the student performs each task and how well each is performed. As necessary, prompting is provided and respective documentation is entered into the table (to indicate prompting as opposed to independent completion). For example, I worked with a client who understood the meaning of the shopping list but started off for the first item without a basket or cart. I engaged him with a discussion about how he would carry the items. At one point I had him hold 7 grapefruits and it became apparent to him that he needed a cart. (I documented this in the document.)

Other issues that arose were parking the cart in the middle of the aisle, finding the appropriate section of the store but struggling to navigate the section for the item (e.g. at one point I prompted him to read the signs over the freezer doors), and mishandling the money when prompted to pay by the cashier announcing the total amount to pay.

Step 2 is to identify a task or sequence of tasks to practice in isolation based on the results of the pretest. For example, this could involve walking to a section of the store and prompting the student to find an item. Data collection would involve several trials of simply finding the item without addressing any other steps of the task analysis.

Step 3 would be to chain multiple steps together, but not the entire task analysis yet. For example, having the student find the appropriate section and then finding the item in the section.

Eventually, a post-test can be administered to assess the entire sequence to identify progress and areas needing more attention.

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