Heads up for Pi day (3/14)

Pi day is upon us in a few days... 3/14. I'll refer you to my earlier post about Pi day for some resources and ideas.

Subitizing - a video review

What is "subitizing"? It's probably a new word for most. It basically means being able to recognize instantly how many objects you see, without counting.

We all do that with the dots on the face of a dice. People who play dominoes with the larger set also learn to do that with the dots on the dominoes (they can go up to 18).

But why would such be important? It is for children, because it promotes number sense, and also ties in with the concepts of addition, subtraction, and even place value.

Look at the dominoes in the picture, and especially the one in the front with turquoise dots on the left side and three orange dots on the right.

Photo courtesy of catheroo

Looking at the turquoise dots, can you tell how many there are without counting?

Most of us realize that it is just one less than three rows of three, or nine. So therefore it has eight dots. That is "subitizing".

By learning to subitize a child is learning:
• number sense
• to associate a number with a whole collection
• to visualize quantities and the associated number
• relationships between numbers
• to visualize subsets of a number
• to use subsets of numbers to quickly make addition and
subtraction equations
• the foundation for quick and creative mental arithmetic
• place value concepts


I recently had the opportunity to watch a video made specifically to address this math concept, called Subitize Me! It is about 28 minutes long and meant for children from PreK to 2nd or 3rd grade.

This is the trailer of the video:




In it, two children go through an adventure of sorts inside ancient ruins where they have to first be able to tell the number of gold coins before they can escape. The children get there through a series of seven "lessons", for example with dice, with a snowman, or spacecraft. In each lesson they learn more and more about subitizing, until finally they are able to see the large number of coins in groups of ten tens (hundred) and groups of tens.

My children liked the movie and wanted to watch it twice (thus far). It is actually recommeded to watch it repeatedly over time so children can cement the concepts shown in the video.

This is a commercial movie on a DVD. The DVD also has some additional exercises for children to watch and think through. You can also purchase (separately) a booklet for the teacher that has activities you can do and has a brief summary of the movie.

The video is well made and ties in with the math concepts very well. I would recommend it to elementary school teachers, libraries, co-ops, math clubs and any such places where many children have the opportunity to watch it.

I'm definitely not against home users (parents) purchasing it, either. This concept is beneficial for all children and teachers! However, I consider it a bit pricey, as compared to other math-related movies and DVDs that are available commercially, because it does not really cover that big a part of the typical math curriculum. So you need to consider your budget. Maybe you could resell it afterwards, which would reduce the cost.

I also hope they would make it available for watching online for a small fee, kind of like how you can "rent" (download) movies from Amazon for a few dollars. That would make it more accessible to larger numbers of parents.

Please see more information about the movie at Movie Makers.

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Disclaimer: I received from Movie Makers company a link to be able to watch this movie for free, plus the PDF version of the teacher activity booklet. I did not receive any other compensation. The opinions are mine.

New Math Mammoth books

There are now three new books available in the Blue Series. They are all for grades 5-6. The material for these books came from the Light Blue 5th and 6th grade curricula. Please click on the links to learn more and see samples.

1. 

   Math Mammoth The Four Operations
   (with a Touch of Algebra)

   The main topics studied in this book are simple equations, expressions that involve a variable, the order of operations, long multiplication, long division, and graphing simple linear functions.
   
   The idea is not to practice each of the four operations separately, but rather to see how they are used together in solving problems and in simple equations. We are trying to develop student's algebraic thinking. Many of the ideas in this chapter are preparing them for algebra in advance.
   
   

2. Math Mammoth Ratios & Proportions & Problem Solving

   This worktext concentrates, first of all, on two important concepts: ratios and proportions, and then on problem solving.
   
   First, we study thoroughly the concept of ratio, including how it connects with fractions and the aspect ratio in rectangles.
   
   Solving proportions is divided into three separate lessons. In the first one, we solve proportions by thinking through equivalent ratios. In the second one, the usual method of cross-multiplying is introduced. Then follows a lesson that explains just why cross-multiplying is allowed. Then there is more practice with solving proportions and word problems. We also study scaling geometric figures and floor plans.
   
   The last lessons concentrate on various kinds of word problems that can be solved with the help of bar or block diagrams (the same kind as in Singapore Math). These involve problems with fractional parts, and then problems involving ratios. The diagrams become a powerful tool to solve such problems without the use of algebra.
   
   
3. 

   Math Mammoth Place Value 5

   Math Mammoth Place Value 5 is a short worktext that covers value up to the trillions—that is, numbers up to 15 digits—rounding them, and using a calculator.
   
   The first lesson covers place value up to billions. Then, we study exponents, and right after that, place value up to trillions, writing the numbers in the expanded form using exponents. After working with addition a little, there are two lessons about calculator usage.