# Adding and Subtracting Fractions in the Real World

## Engaging Your Students with Food: Fractions in the Real World

When it comes to Fractions in the Real World, one guaranteed way to get kids to participate in class is to use food.  Yes, food. I believe that food is the universal means to get participation by any group of people – especially kids!  No matter the demographic or ability level, all kids love food.  Although it takes a lot of effort on your part up front, it is a great way to get kids engaged when teaching a more abstract concept like fractions. This also helps make the concepts discussed more concrete and tangible. This lesson comes at the end of a unit where you have already taught this concept, but you will have students who need the reminder.

## The VERY Strict Rules for this Adding and Subtracting Fractions Activity:

Of course I recommend laying down some pretty strict ground rules so that the lesson will be a success.  I find that if the kids know they get to have a treat in the end, they will listen.  Here are the rules I use in my class for the Fractions in the Real World Activity:

1. Eat only when instructed to.
2. Food that touches the desk or the ground goes directly into the garbage.
3. Do not share or switch food with other students.
4. Follow directions so that food is not contaminated.
5. Wear your gloves at all times.

There are also some safety rules to keep in mind when using food.  Be sure you know each students’ health status and are aware of any allergies.  Stay clear of those foods that are a risk. There are plenty of foods that are safe for kids who have allergies.

## Set Up for the Lesson: Adding and Subtracting Fractions in the Real World Activity

• Each student needs their math notebook or a piece of paper
• One large bowl for each trail mix ingredient
• Trail Mix ingredients
• Various sizes of measuring cups – if you do not have standard measuring cups, you can mark clear plastic cups with a permanent marker to the appropriate amounts – ½, ⅓, ¼
• One large bowl for each group to blend their trail mix
• A large mixing spoon for each group
• Plastic gloves – one pair for each student

## How to Launch the Adding and Subtracting Fractions in the Real World Lesson

### Step 1:

Start with a well known fruit, like an orange.  Have it pre peeled, but still together.  Most oranges have 10 sections on the inside.  This is an easy denominator to work with.  If you are worried about it being different than 10, have it peeled and sectioned beforehand.  Ask students to guess how many parts are in the orange.  Write their guesses on the board.  Then break the orange in half.  Ask students for the fraction you just created.  Draw a picture and write the fraction on the board.  Ask them to imagine sharing this orange with one friend.  How much of the orange would each of you get?

### Step 2:

Then, with great fanfare, take the sections apart.  Count them together.  Ask the students for the fraction of one of the sections, compared to the whole. Write it on the board.  Ask again, if you shared this orange with one friend, how much of the orange would each of you get, based on our new base fraction.  Each student would get 5/10.  Ask students to add this together in their notebooks.  Write it on the board as a class so they can check their work.  5/10 + 5/10 = 10/10 or 1 whole.

### Step 3:

Now ask the students how they would share this orange with two friends.  As they give you ideas, make groups of the orange.  Write the new fraction, the amount given to each person, on the board. 3/10 + 3/10 + 3/10 = 9/10.  Ask students if this is a whole?  How would they share the remaining 1/10 section of orange?

### Step 4:

Point out to students that this work they have done was adding fractions with like denominators.  Ask them how they would create a real world situation where students were using subtraction to solve a problem.  Some examples they may give are:

• I have an orange. I give 4/10 of it to my brother.  How much do I have left?
• My friends each want some of my orange. There are 4 of them. How much of the orange do we each get?
• I am hanging out with two friends. Two of us have an orange.  If we wanted to share half of our orange slices with the other friend, how much of the oranges would they get?

## The Lesson: Fractions in the Real World

Now we get to the fun part!  Divide students into groups of 5 or 6.  Give one recipe worksheet to each person. I like to have  each student use their own worksheet – that way everyone does the work. Students can come together at the end to check each other’s work, and they can help each other if they get stuck.

### Share

Introduce the activity to the class.  Just like we shared the orange, today you are going to share something yummy…trail mix!  Each group will follow the recipe on your worksheet.  You will then find the total amount of trailmix you have and how much each person in your group will receive.  You may not eat any of your trail mix until the teacher has verified that your math is correct.  You must write out the equations for figuring this out.  Even if you do the work in your head, you will need to show your work when you write down the answer.  I always like to see my students’ written work so I can assess their thought process.

### Review

Review how to add and subtract fractions with unlike denominators.  Leave your example on the board as a reference for students as they work.  *Make sure there are more or fewer cups of trail mix than the number of students in a group.  The number of cups should not be equal to the number of kids in the group.  For example, if there are 6 people in a group, the most total trail mix should be 5 ½ cups.

### Recipe

I used the recipe from the site https://www.iheartnaptime.net/kids-trail-mix/.  I did eliminate peanuts/nuts, because it is a common allergy.

### Steps for each group:

1. Wash your hands with soap.
2. Put on plastic gloves.
3. Assign one person in your group to each ingredient.
4. Send one person at a time to get the correct amount of each ingredient and add it to your group’s bowl.
5. Mix all of your ingredients together using the large spoon.
6. Complete the questions on your worksheet.
8. Distribute trail mix to baggies.

## Reflecting on the Fractions in the Real World Activity

Of course you are probably going to start by talking about how fun it is to eat food in class!  Then ask students what problems they faced?  Some may have found that when they shared the trail mix, they had some left over.  Ask students how they solved the problems? Did they throw the leftover away?  Did they find a way to share it equally? Point out to students that in these cases they had to find a common denominator.  How did they do that?  How did they decide on the denominator based on their groups?  Finally, let them eat their trail mix!  Yum!

## Extensions/Next Steps

Although students are focusing on adding and subtracting fractions in this activity, many of them will have noticed that the repeated addition and subtraction is also multiplication and division.  Your next step could be to have the students rewrite the repeated addition and subtraction as multiplication.

You could ask them to find out how much trail mix would be needed if your group made this trail mix 2 times a week?  Three times?  Or how much would each student get if you cut the amount in half?  Or by thirds?

## Supplemental Resources: Fractions in the Real World

https://www.iheartnaptime.net/kids-trail-mix/

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