Sensational Smoothies: Metric (Day 2)

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SWBAT convert grams to kilograms, & solve multi-step, real world problems.

Big Idea

Help Amy make smoothies by converting grams to kilograms; you wouldn't want her smoothies to taste badly!


10 minutes

We use Flocabulary's Song The Metric System to review. This site provides a rap style song that my students love, and really get into, and love singing along to. So long as they don't get carried away, I allow them "get down" with it too, and use motions because that helps trigger memory. (I don't specifically tell them what moves.) I let my students listen to the song one time, and then sing along as I play it a second time . Throughout the week, I put this video on during some transitional times for extra practice too. Most of the songs on here are incredibly catchy, and students sing the songs to themselves long after they've heard them. The site provides the lyrics, a quiz, and extension activities. Each song is linked to CCSS too. This song is free, but most of the site is a subscription. I have students listen only the first time, and then then can sing along the second time they hear the song. Sometimes I throw in one of the songs I've used during a transitional time in the classroom.

Guided Practice

15 minutes

Amy is making smoothies. She uses 1.2 kilograms of apples and 600 grams of strawberries. How many kilograms of fruit does Amy use in all?

I first set my expectations for the students by telling them that today, tomorrow, and the day-after tomorrow they will use these steps. By modeling this I am creating connections so that students will recognize that there is a pattern to problem solving, and it's a procedure to follow. (There's not just a quick answer.) I'm trying to build up their endurance and patience in problem solving.

To tackle this problem, students make sense of the quantities and the relationship among metric units (MP2). I anticipate students will have trouble with, and need practice in, determining the first step on their own.

So I begin with some prompting. A kilogram is _______, so you need to _______.
My goal is that with this initial explicit practice, they'll be able to begin working on their own. I model each of the 3 steps here:

A) Convert 600 grams of strawberries to kilograms.

1 kilogram = 1000 grams

A kilogram is _____ than a gram, so you need to _______.

_______  _____ 1000 = _______

600 grams = ________ kilograms

B) Add kilograms of apples to kilograms of strawberries.

1.2 kilograms + _______ kilograms = ______ kilograms

C) Amy uses _______ kilograms of fruit in all.

We list the givens of the problem, and circle them on the board. Using cold calling, I use student input to lead us through the explanation. By modeling this, I hope that students will use this step-by-step strategy in their future problems. 

Independent Practice

15 minutes

Now, you want to determine how many grams of fruit are used, instead of kilograms. How could you do this?

Using MP1, students make sense of problems and persevere in solving them. Students determine an approach to a conversion problem.

Using MP2, students reason abstractly and quantitatively. Students make sense of the quantities in a problem and the relationship among metric units to solve a problem.

At first my students groaned, as they initially thought that this was going to be quite difficult.  Allowing them to work with their table partner, they quickly realized this was pretty simple. You can convert 1.2 kg of apples to grams. You can then add the grams of apples to grams of strawberries.

In the video, you'll hear two students working through this that explain that "it's actually easy", and you'll hear the sentence frame that we used in the Guided Practice that leads the conversation. 

This was definitely a teachable moment which built up their math "endurance". Often times, my students give up on a problem if it requires more than one step.


10 minutes

As a class, we connect Math to cooking. We collaborate to write a cake recipe using random ingredients, measured in grams. While the objective is serious, the ingredients can be zany! For example, 400 grams of chewing gum.

As the students call out ingredients, I write them on the board with the given amount. Next, students work with their table partners to convert the amount into milligrams. I know that my students love being silly, especially with MadLibs, so I knew that my students would love making up silly ingredients.