Teaching about tax, tip, discounts and interest is a fun, real world topic. As I was teaching it I noticed that my 7th graders don’t actually know much about spending money. Their money spending experience is very limited and that led to some pretty awesome conversations. Like most topics, they entered the learning as essentially blank canvases. I love topics like this because they don’t have a whole lot of misconceptions when we start learning. So, to get started with planning this unit, I first chunked out the unit by writing our learning goals as “I Can” statements. These become the backbone of my lesson planning. Everything starts with the answer to the question, “What do I want my students to be able to know and do?” Below I will share how I used “I Can” statements to chunk out the learning for working with tax, tips, and discounts.
What I want my students to be able to do with tax, tips, and discounts
As you can see, this concept ends in students being able to apply math skills to real world story problems. They have to be able to find whether there is an increase or a decrease and then do something with that information. Students seem to struggle the most with the application portion of this topic, so that is the area that requires a lot of focus.
One challenge for this unit is that it was my first time teaching this topic from start to finish. It is something that comes extremely easy to me and I can do all the work in my head. Sometimes when you know the topic too well you have what is known as the curse of knowledge. Unfortunately, I definitely had this the first time I taught this. I made way too many assumptions about what students understood. The unit didn’t go well, so I had to go back to the beginning and reteach it to the class. The second time around my students really did well. I’m going to share what I did the second time that was super successful.
I can statements
When I sit down to plan a unit I chunk out the lessons through writing “I Can” statements. You can read more about this process in this post. Here are the I can statements that I had my students write in their notebooks for tax, tips, and discounts.
- I can solve for x in a proportion.
- I can set-up a proportion to find the value of a proportional tax, a tip, or a discount.
- I can identify if the situation represents an increase or a decrease.
- I can read and annotate a story problem related to tax, tips, or discounts and identify which operations are happening.
- I can find a total in a story problem related to tax, tips, and discounts.
This is not a perfect list. Remember, it is a starting place for the unit and you can change it as you go. I don’t always word them exactly the same way from class to class. The best part, though, is to have a road map that will lead from a starting place to a finish. Next, let’s examine how each of these I can statements can help you in your planning and teaching of tax, tips, and discounts.
I can solve for x in a proportion.
This is a topic that students have learned previously in the year. We have used a lot of practice to help with cyclical review on this topic because it is at the core of many of the other objectives for the year in 7th grade. This I can statement specifically focuses on solving for x in a proportion. This is a concept that is great to review in an anticipatory set to make sure that students can do this with automaticity. If they can’t do this then they will be stuck later on in the unit.
I can set-up a proportion to find the value of a proportional tax, a tip, or a discount.
This was a new way of finding tax or tip for me, but it worked so well for my students because they have a deep background in setting up and solving proportions. I was trying to teach them how I do it in my head. Something that I have been doing for years and don’t have to think about. I found out real quick that this was beyond their zone of proximal development, if you will.
This is how we set up the proportion. We always put the percent first and it is the number per 100. Then, we write an equals sign and the other fraction will always have x as a numerator and the amount we are finding the percent of will be the denominator. It can be tempting to teach multiple ways of doing it, but if it is new to students, less is more.
Someday they will be ready for learning a variety of ways to do it, but for now one way that makes sense to them is enough. Especially considering that we have such a short amount of time to learn this topic.
I can identify if the situation represents an increase or a decrease.
This is a small objective, but important nonetheless. I realized that 7th grades don’t have a huge background with taxes and tips. They are not usually the ones footing the bill at dinner. Also, I work at a low income school and many of the kids don’t go to a lot of restaurants where you pay a tip. We had to spend some time practicing which situations are markups and which ones were markdowns.
I can read and annotate a story problem related to tax, tips, or discounts and identify which operations are happening.
This is an aspect of problem solving that we are emphasizing at my school this year. We need to give students more experience and strategies for reading and understanding problems. One way to do this is for students to annotate problems. We use a strategy called C.U.B.E.S. This stands for:
- Circle the key numbers
- Underline the question
- Box any math action words
- Eliminate information that is not needed
There are other ways to do this. I think the most important thing is to have a way of reading problems and use it consistently. Don’t assume that students can do anything and remember that if they can’t do it, then you have to teach it to them.
I can find a total in a story problem related to tax, tips, and discounts.
This is the culmination of all the other work. In this part students have to put it all together. If the other parts are done well, then this part should come together. Here students solve story problems which can come in different levels of difficulty. They may just have to find the tax and add it to the original price. Or they may have to add more than one markup or markdown. Also, you might want to have students just spend time before diving in to a problem identifying if they are going to add or subtract. Sometimes, they may have to use other operations too.
Misconceptions about taxes, tips, and discounts
Finally, the biggest misconception that I saw will my students is that they are used to thinking of going down as bad, so they think that tax goes down. I have one students in particular who would argue with me on almost every problem about why we have to subtract a discount. She really just wanted to add the discount because she felt like she was getting extra money with a discount. I never expected this misconception, but for some of my students it is pretty deep.
Take-Aways and Getting Started
Chunking the learning through I can statements can help you to go in a logical order that will lead to deep understanding for your students. The I can statements that I have are not the only way that this can be taught. You can adapt them for your students and your standards. I love having students write them in their interactive notebooks and reflecting on them throughout the unit. It helps students to be aware of what they learning while helping me keep them on a good path.
If you are interested in a resource that progresses in an order like the one described above check out our task cards for taxes, tips, and discounts.
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