# Surf for More Math

## Lesson 9 - Trading Bills

To encourage students to have fun on the Web while learning about Trading
Bills, here are some games and interactive activities they can do on
their own or in pairs.

**Goal **

Explain the trades you can make with bills up
to $100.

**Builds Upon **

Student Book pages 44-46

**Instructions for Use **

Change
Maker provides students with practice counting money and estimating
differences.

To use Change Maker, choose a currency by clicking on the flag of a
country, and a difficulty level. Mentally subtract how much money you
expect to get back when you pay for an item. If you get the answer correct,
the amount of change is added to your piggy bank. If you get the answer
wrong, the correct amount of change is subtracted from your piggy bank.
The more money you get in your piggy bank, the harder the questions
will get.