# Surf for More Math

## Lesson 1** - Adding and Subtracting Whole Numbers **

To encourage your child to have fun on the Web
while learning about Adding and Subtracting Whole Numbers, here are
some games and interactive activities they can do on their own or in
pairs.

**Goal**

Use mental math strategies to calculate sums and differences.

**Builds Upon**

Student Book pages 106-107

**Instructions for Use**

** **

Adding
and Subtracting Mentally lets your child practice using mental math
strategies to add and subtract.

To use Adding and Subtracting Mentally, select a topic - either addition
or subtraction. Then select the level of difficulty - green is easy,
yellow is difficult, and red is the most difficult. Click the 'Begin!'
button to load the first of ten questions. Input the answer in the text
box and press 'Enter'. The tally on the screen shows your results.

Base
Block Addition lets your child practice addition with and without
regrouping.

To use Base Block Addition, drag a base block into a column to the
left. If your child moves a block one column to the right, it breaks
apart to show the exchange, for example, a 10-long for ten units. To
group pieces to exchange in the other direction, click and hold the
mouse key down while dragging a rectangle to "lasso" the pieces.
The newly grouped object can then be dragged into the next column.

To complete a preset addition problem, select base 10 and click on
the 'Next Problem' button. Group any pieces and drag them into the next
column. Start with the 1s column and work to the 1000s column. The addition
solution will appear on the left.

To add the blocks together to create a problem, click on the 'Create
Problem' button, and then use the blue buttons at the top to enter blocks
above and below the dashed line. As long as there are two numbers correctly
represented in the specified base, the addition problem will appear
on the left. To solve it, click on the 'Begin Problem' button, and then
on any of the blocks in the workspace.

Adding
Whole Numbers prompts your child to use a paper and pencil to add
4-digit numbers.

To use Adding Whole Numbers , click the 'Start Addition' button. Using
paper and a pencil, place the number to be added below the first number
so that the thousands, hundreds, tens, and ones places are aligned.
Draw a line under the bottom number. Add the bottom place digits from
the top ones and regroup where necessary. When your child has finished
adding the numbers, input the answer in the text field and click 'Check'.