Math Debate: Adding Fractions

Cover image by Thor/ geishaboy500 via Flickr (CC BY 2.0)

I’ve been working on my next Playful Math Singles book, based on the popular Things to Do with a Hundred Chart post.

My hundred chart list began many years ago as seven ideas for playing with numbers. Over the years, it grew to its current 30+ activities.

Now, in preparing the new book, my list has become a monster. I’ve collected almost 70 ways to play with numbers, shapes, and logic from preschool to middle school. Just yesterday I added activities for fraction and decimal multiplication, and also tips for naming complex fractions. Wow!

Gonna have to edit that cover file…

In the “Advanced Patterns” chapter, I have a section on math debates. The point of a math debate isn’t that one answer is “right” while the other is “wrong.” You can choose either side of the question — the important thing is how well you support your argument.

Here’s activity #69 in the current book draft.

Have a Math Debate: Adding Fractions

When you add fractions, you face a problem that most people never consider. Namely, you have to decide exactly what you are talking about.

For instance, what is one-tenth plus one-tenth?

1/10 of 100

Well, you might say that:

\frac{1}{10}  of one hundred chart
+ \frac{1}{10}  of the same chart
= \frac{2}{10}  of that hundred chart

But, you might also say that:

\frac{1}{10}  of one chart
+ \frac{1}{10}  of another chart
= \frac{2}{20}  of the pair of charts

That is, you started off counting on two independent charts. But when you put them together, you ended up with a double chart. Two hundred squares in all. Which made each row in the final set worth \frac{1}{20}  of the whole pair of charts.

So what happens if you see this question on a math test:

\frac{1}{10}  + \frac{1}{10}  = ?

If you write the answer “\frac{2}{20}”, you know the teacher will mark it wrong.

Is that fair? Why, or why not?


CREDITS: Feature photo (above) by Thor/geishaboy500 via Flickr (CC BY 2.0). “One is one … or is it?” video by Christopher Danielson via TED-Ed. This math debate was suggested by Marilyn Burns’s blog post Can 1/3 + 1/3 = 2/6? It seemed so!

howtosolveproblemsWant to help your kids learn math? Claim your free 24-page problem-solving booklet, and sign up to hear about new books, revisions, and sales or other promotions.

Funville Adventures: Blake’s Story

Today we have a guest post — an exclusive tale by Sasha Fradkin and Allison Bishop, authors of the new math storybook Funville Adventures. Enjoy!

Funville Adventures is a math-inspired fantasy that introduces children to the concept of functions, which are personified as magical beings with powers.

Each power corresponds to a transformation such as doubling in size, rotating, copying, or changing color. Some Funvillians have siblings with opposite powers that can reverse the effects and return an object to its original state, but other powers cannot be reversed.

In this way, kids are introduced to the mathematical concepts of invertible and non-invertible functions, domains, ranges, and even functionals, all without mathematical terminology.

We know about Funville because two siblings, Emmy and Leo, were magically transported there after they went down an abandoned slide.

When they came back, Emmy and Leo shared their adventures with their friends and also brought back the following manuscript written by their new friend Blake.

Continue reading Funville Adventures: Blake’s Story

Check Out These Cool Math Sales

I’ve been following Sonya’s Arithmophobia No More blog for a couple of years, and I love the work she is doing. But this month, she’s teamed up with Lacy at Play, Discover, Learn (another great blog to follow!) to offer a humongous bundle of playful math.

You get math journaling pages, games, creative task cards, thought-provoking worksheets, and video training resources to help you build your child’s understanding of math from arithmetic to early algebra. Wow!

These activities are perfect for homeschooling families or anyone looking to supplement their child’s current math curriculum with effective discovery-based activities. If you’ve ever wondered what to do with those Cuisenaire rods you picked up on sale way back when, this bundle is for you.

I’m so looking forward to using some of these ideas with my elementary homeschool co-op kids next year!

Sale price is $30 from December 2-15.

Cuisenaire Rod Activities Blowout Bundle

But Wait, There’s More

If you’ve been reading my blog for very long, you’ve probably seen how much I love the blog, books, and classes available from the Natural Math folks.

Their newest book is just off the presses — Funville Adventures, a math adventure chapter book.

And until December 20, they’re having a holiday sale. Make your own bundle of any Natural Math books. Playful algebra, calculus for 5-year-olds, inquiry problems and more: Great deal!

Natural Math Book Sale

Stock Up on My Playful Math Books

Finally, if you’ve been wanting to pick up a paperback copy of Let’s Play Math or some of my game books, or maybe a set of dot-grid math journals, I’m currently offering a discount on bulk orders.

Bundle ANY assortment of titles. Stock up on books for your family, friends, or homeschool group.

  • 2–4 books: 15% discount off retail prices
  • 5–9 books: 25% discount
  • 10–19 books: 35% discount
  • 20+ books: 35% discount, and free Continental U.S. standard shipping or the equivalent discount off other shipping options

Bulk Order Playful Math Paperbacks

(US customers only: We’re sorry we can’t offer bulk discounts for our international readers, but the complexities of international duties and tax laws are too much for this very small family business.)

Do You Know of Any Math Deals?

Apollonian greetings from my homeschool co-op kids, and best wishes for a grace-filled holiday season.

If you’ve seen a great deal or holiday price on a math resource you love, please share!

Add your deal to the comment section below, so we can all take advantage of the math joy this season.


howtosolveproblemsWant to help your kids learn math? Claim your free 24-page problem-solving booklet, and sign up to hear about new books, revisions, and sales or other promotions.


How to Talk Math With Your Kids

A friend shared this video, and I loved it! From Kent Haines, a father who happens to also be a math teacher…

“I hope that this video helps parents find new ways of interacting with their kids on math topics.”

Kent Haines

More from Kent Haines

Advice and Examples of Talking Math with Kids

Danielson-Talking Math

If you enjoyed Kent’s video, you’ll love Christopher Danielson’s book and blog.

It’s a short book with plenty of great stories, advice, and conversation-starters. While Danielson writes directly to parents, the book will also interest grandparents, aunts & uncles, teachers, and anyone else who wants to help children notice and think about math in daily life.

“You don’t need special skills to do this. If you can read with your kids, then you can talk math with them. You can support and encourage their developing mathematical minds.
 
“You don’t need to love math. You don’t need to have been particularly successful in school mathematics. You just need to notice when your children are being curious about math, and you need some ideas for turning that curiosity into a conversation.
 
“In nearly all circumstances, our conversations grow organically out of our everyday activity. We have not scheduled “talking math time” in our household. Instead, we talk about these things when it seems natural to do so, when the things we are doing (reading books, making lunch, riding in the car, etc) bump up against important mathematical ideas.
 
“The dialogues in this book are intended to open your eyes to these opportunities in your own family’s life.”

— Christopher Danielson
Talking Math with Your Kids


CREDITS: “Kids Talk” photo (top) by Victoria Harjadi via Flickr (CC BY 2.0). “Parent Rules” by Kent Haines.

howtosolveproblemsWant to help your kids learn math? Claim your free 24-page problem-solving booklet, and sign up to hear about new books, revisions, and sales or other promotions.


10 Ways to Play Math with Play-Doh

Today we have a guest post from Lucy Ravitch, author of the new Kickstarter picture book Trouble with Monkeys: A math concept story of place value. She’s sharing a few ideas from her Math Activity Thursday (M.a.Th.) video series. Enjoy!


Hello, math fans and enthusiasts! Each week I try to give you and your family a fun math activity to try. Two months ago I posted this video with ten ways to turn play dough into an engaging activity for lower and upper elementary math.

If you want to make your own dough from scratch here are a few simple recipes. I encourage you to let your children play freely at first, before trying these activities.

Below I have identified some of the math concepts that your kids will experience as they play.

1. Toss It

Practice counting. With older children, record your results and make a graph of the data.

  • How many times can you catch it in a row? What’s your average number of tosses?
  • Talk about attributes. Does the size or color of the play dough balls make a difference?
  • How high are you tossing it? Talk about measuring systems. Do you use feet and inches, or meters and centimeters?
  • If you know how to juggle, time how long you can keep the balls going.

2. Smash It

Make several small balls or pieces. Then play as you smash them.

  • Play a NIM game: Make 10-15 small play dough balls. Take turns. On your turn, you can smash one ball or two. Whoever smashes the last ball wins the game.
  • Or smash your math facts: Choose several equations for your children to practice. Write each answer on a 3×5 card. Lay out each card next to a play dough piece. As you call out the equations, kids smash the play dough next to the correct card.

3. Shape It

Have fun molding your play dough. Roll it out to cut shapes.

  • Try making 3D shapes while practicing your math vocabulary. MathisFun.com has a great section about solid geometry. Can you find three math terms that are new for you?
  • Roll out the dough and cut 2D shapes. Discuss their attributes. Can you cut your shape in half to be symmetrical?

4. Hide Things in It

Find small objects around the house and enclose them inside play dough.

  • Take turns hiding small objects in play dough. Optional: Give a one-minute time limit to guess before opening it. This gives you and your kids a chance to talk about size, shape, or other attributes.
  • Have challenges to use the least amount of dough to hide identical objects. Two players have two minutes to hide an object in as little play dough as possible. The object must be completely concealed within the dough. What methods will you use?

5. Make Imprints on It

Show off your design skills and observe textures.

  • You can practice counting as you poke and press your fingers or objects into the dough. Older children can discuss the distance between impressions and/or the pressure applied.
  • As you and your kids make designs, talk about what you notice: Is your design symmetrical? What tools did you use (toothpicks, pencils, marbles, fingers, toy cars)? Which objects make interesting textures?

6. Cut It

Use a butter knife or the edge of a ruler to cut your play dough. Discuss findings as you play and explore.

  • In the video, I posed the question: how many sections do you get if you make only three cuts? Try it and see.
  • Does the number of pieces change if you use a shape other than a flat circle?
  • Discuss making straight cuts that will intersect or be parallel. Bring in more geometry terms.
  • Experiment with a different number of cuts.

7. Weigh It

Pull out a kitchen scale or balancing scales to use with dough.

  • Older children can make conversions between ounces to grams. They can make calculations about doubling or multiplying the measured weight. With younger kids, try using balancing scales. Compare the weights between pieces.
  • Try making two pieces that weigh exactly the same. This is harder than it sounds! For small children, this gives them the opportunity to see that the mass (weight) of an object can come in different shapes.

8. Measure It

Use a ruler or measuring tape while you play. There are several ways you can measure your dough — height, width, and length.

  • How long can you extend one ounce of dough? Pick your own size/weight of play dough and see who can get the longest. What fraction of a yard or meter is it?
  • Discuss height and what it takes to make dough stand vertically. How tall can you get three ounces to stand? Can anything help make it taller?

9. Roll It

Make sure you have plenty of room for this activity. Playing outside or on smooth floors works best.

  • With one push how far does your play dough roll? Is there an ideal size for a piece? Is there an ideal weight for rolling?
  • Is the ground sloped? What effects does the rolling surface have?
  • Why do some shapes roll easily while others don’t? Can you create a not-round shape that will roll?

10. Compare It

Compare similarities and differences between dough colors and types. Consider comparing the previously listed activities

  • If you made your own dough, compare consistency between batches. Is homemade dough denser or lighter than store-bought dough?
  • What are differences between the dough you played with and the dough that has not been touched?
  • Which of these activities do you think will take the shortest amount of time? The longest? Or put the activities in order based on how much dough you will need — least to greatest.

May you and your students have fun as you play with dough!


About the Author

Lucy blogs at kidsmathteacher.com and is the author/creator of Kids Menu Books. The first book in that series is The Pancake Menu, an interactive book that lets kids practice math as they play restaurant.

And be sure to visit Lucy’s Kickstarter project! She’s teamed up with artist Trav Hanson to create the delightful picture book Trouble with Monkeys: A math concept story of place value.

Even a Math Workbook Can Be a Game

Homeschooling Memories…

My youngest daughter wanted to do Singapore math. Miquon Red was her main math text at the time, but we added a bit of Singapore Primary Math 1B whenever she was in the mood.

We turned to the lesson on subtracting with numbers in the 30-somethings.

The first problem was pretty easy for her:

30 − 7 = _____

I reminded her that she already knew 10 − 7.

She agreed, “Ten take away seven is three.”

Then her eyes lit up. “So it’s 23! Because there are two tens left.”

Wow, I thought. She’s catching on quickly.

Mom Always Talks Too Much

We went to the next problem:

34 − 8 = _____

“Now, this one is harder,” I said. “But you know what ten minus eight is, right? So we could take one of these tens and—”

She waved at me to be quiet.

I was just getting started on my standard speech about how to turn a tough subtraction like 34 − 8 into the easy addition of “2 + 4 + two tens left.” But her mind was still on the last problem, specifically on the two tens and the seven.

“If you have 27,” she said, “and you add three more, you get 30. And four more is 34.”

“Um, yes, but…” I interrupted.

She shushed me again.

“And then you can take away the four. And then you can take away the three. And then you can take away one more…It’s 26!”

Mom Learns a Lesson

She continued through the next page that way. For every problem, she started with whatever number struck her fancy, usually containing at least one digit from the problem before. She added enough to get up to the 30-something number in the book.

Only then would she deign to subtract the number in question.

I don’t think she ever saw the point of the mental math technique the book and I were trying to teach, but she did have a lot of fun playing around with the numbers.

In the long run, that’s much more important.


Feature photo: “Laughing Girl” by ND Strupler via Flickr (CC BY 2.0).

howtosolveproblemsWant to help your kids learn math? Claim your free 24-page problem-solving booklet, and sign up to hear about new books, revisions, and sales or other promotions.