Place value disks activity: learn addition and subtraction with large numbers

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1 Place value disks activity: learn addition and subtraction with large numbers Our place value system can be explained using Singapore Math place value disks and 2 mats. The main rule is: value depends on place. One column to the left makes the value ten times as much. So one disk in a column to the left has the same value as ten disks in the column to the right. Show some examples: red disks have the same value as one orange disk, and green disks have the same value as one blue disk. We can also go from larger to smaller values: one red disk can be traded for white ones. Order the disks in columns according to value Start with a pile of place value disks and count together with your child, start with small numbers. Model to order the disks on the mat as the example on page : counting is much easier now. Explain you always start with the numbers in the three columns on the right: ones, tens, and hundreds. They are separated by a comma from next three columns to the left: the thousands. The thousands are again separated by a comma from the next value: the millions. Go from calling the disks by their color to name them by value. The goal is to help your child counting in tens, hundreds, thousands, etc. instead of only in ones. Write the number in the bottom row Count the number of disks in each column and write it in the bottom row. Say: "I count 2 'thousand disks', so I write a 2 in thousands place". When there is no disk for a column, we keep the zero(s) in the middle and to the right. This shows where the number 'ends' so we know which is the 'ones' column. We do not need to write all zero's to the left. Read and say the number Mention the names of the columns from right to left and show the numbers on a disk from each column. Explain that to read a number out loud in words, we start with the largest place value, so on the left: 4,702,053 is four million, seven hundred and two thousand, fifty three. Go from disks to written numbers, and back. Go from written to read out loud numbers and back. Too many disks for a column? Make trades! Show that there are 9 places in each column. When there are more than 9 disks of a color, you need to 'trade' (exchange) of those disks for one disk of the color in the next column to the left. Remember the value of one disk in a column to the left is the same as the value of ten disks of a column to the right. Calculations with the disks using two empty mats Addition Make a number with disks as above on one mat (on the left side), write and read the number. Make a new number on the other mat (right side), write and read that number. Now add them together on the first mat. Say "3 hundreds and 2 hundreds make 5 hundreds". Make trades as necessary. Write and read the added total.

2 Subtraction Make a number as above on the first mat, printed sides up (on the left). Make a number with disks printed side down on the other mat (right). Bring the same number and color of disks from the first mat to cover the disks on the second mat to show we are 'taking away' that number. Start with subtraction without trades, than include trades. Ask your child to show you how it works. Ask how it can be explained to a friend who does not know this yet. Ask your child to come up with more numbers for calculations. Can he do the same on an empty inch squares mat and write and say the number? Order your Singapore Math Place Value Disks at Crystal Springs Books or make it a fun activity to write numbers on colored foam disks with a sharpie together with your child. This activity will help memorizing and draws attention to the number of zero's. You can also use the template below:,, 0,, 0,, 0,, 0,, 0,, 0,, 0 DyscalculiaServices.com for more free activities visit activities and downloads

3 Million Hundred th. Ten thousand Thousand Hundreds Tens Ones ,, 4, 7 0 2, 0 5 3

4 Million Hundred th. Ten thousand Thousand Hundreds Tens Ones , 0 0 0, 0 0 0

5 Million Hundred th. Ten thousand Thousand Hundreds Tens Ones , 0 0 0, 0 0 0

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