Calculating in standard form

What this chapter teaches

In standard form the front numbers and the powers of ten are two separate jobs. Multiplying multiplies the front numbers and adds the powers, and dividing divides and subtracts. Adding needs both powers made equal first. After any sum, the front number must be put back between 1 and 10.

Three questions to ask

There is no one right wording. Listen for the idea.

1. Why do you add the powers when you multiply, but not when you add?
2. What do you do when the front number comes out as 30?
3. How do you find how many times wider the Earth is than a cell?

After the chapter, the learner can

• Multiply and divide numbers in standard form
• Add numbers in standard form by matching the powers
• Compare the size of a cell with the Earth in standard form