### Some key spreadsheet concepts and ideas include:

1. Charting of data in the spreadsheet helps students in visualizing the ideas and in communicating their results.
2. Spreadsheets can be used to explore multiple connected representations of tables of data that are created by entering formulas (symbolic representations) that are then dynamically connected with charts. Students are able to make connections among the various representations and see how a change in the table, dynamically updates the chart as they explore particular mathematical ideas.
3. In designing spreadsheet to solve mathematics problems, plan to use this solution beyond the specific problem. Design the spreadsheet to be dependable for extending the knowledge for the problem.
4. Design dynamic spreadsheets that are descriptive of the more general situation so that the spreadsheets can be used to model different cases. For example, create a spreadsheet that can be used to explore multiple linear function problems.
5. Using the ROUND function to two decimal places causes the computer to change the internal value to have only those two decimal places; alternatively, formatting the cell to display two decimal places only changes the visual presentation. The internal value for future calculation is unchanged.
6. Designing spreadsheets that are dependable under changes in the data and key variables in the model.
• Use spreadsheet built-in formulas rather than relying on user-defined formulas since these formulas typically ignore blank cells. On the other hand, user-defined formulas often assume a blank cell contains the value of zero (0).
• Create formulas that reference cell names rather than embedding particular numeric values.
Avoid formulas that embed the values like the 8 in this formula:
= SUM(B2:B10)/8
Refer to values by the cell names in which the values are stored. Spreadsheet uses the values in cells B2 through B10 and B1 in computing the value
= SUM(B2:B10)/B1
• Spreadsheets rely on relative referencing when copied to other cells. If A2 have the formula =B2-C 3and this formula is copied to D2, the formula changes to =E2-F3, and if this formula is copied to M4 the formula becomes =N4-O5 to reference the row and column shifts.
• Use absolute referencing to maintain a cell reference when copying the formula. If A2 has the formula =\$B\$2 - C3 is copied to D2, the formula in D2 becomes =\$B\$2 - C3 and if copied to M4, the formula is =\$B\$2 - O5. The dollar sign (\$) before the column letter means maintain that and do not change it when copying to another cell; the dollar sign (\$) before the row number means maintain that number and do not change it when copying to another cell.
7. Test the spreadsheet with different data is as important as "checking a solution" done by hand. Try different values to assure that the formulas return the desired results.