We have been using cell addresses informally until now, but now we can be more formal and explicit. Different spreadsheets have different types of address bars, but all use the same format, letters for columns and numbers for rows with letters first and numbers second. We introduce this on the hundreds table which could be thought of as a miniature spreadsheet and use number lines to provide some additional feedback. Using addressing enables us to build rules as patterns and to put anything we want into cells to use those rules on. It is the great power of spreadsheets.
Number Lines introduce students to functional thinking and the use of formulas in spreadsheets. For younger students we call these formulas “rules” and ask students to build a variety of number lines using rules. For example they can build a whole number line by creating a rule that adds 1 to the number in the previous cell (=J9+1) and then copy that rule across the numberline cells. They build numberlines with only odd numbers, even numbers, and starting with different numbers. We encourage them to explore a variety of rules to make different numberlines.
In introducing Spreadsheets we want you to learn to build a numberline by using a rule (a formula). We begin with a simple rule that you can copy and paste into the entire numberline. Then we want to add an input from another cell into the rule to give you a chance to change the numberline. And finally you build a rule that lets you change not only the input number but the operation so that you can build any numberline you want. Remember that you have three ideas in functional thinking, an input, an output, and a rule to change the input into the output.