Using a spreadsheet to make predictions USING A SPREADSHEET TO MAKE PREDICTIONS

Transcription

1 USING A SPREADSHEET TO MAKE PREDICTIONS 1

2 QTP 3.2 Using Learning Technologies In English, PDHPE, HSIE and Primary Printed January 2003 Published by Quality Teacher Program (QTP) Bridge St Sydney NSW Australia Commonwealth of Australia 2002 Internet: RESTRICTED WAIVER OF COPYRIGHT The printed material in this publication is subject to a restricted waiver of the copyright to allow photocopying of the material contained in this publication for use within a school, subject to the conditions set out below. 1. All copies of the printed material shall be made without alteration and abridgment and must retain acknowledgment of the copyright. 2. The school or college shall not sell, hire or otherwise derive revenue from copies of the material, nor distribute copies of the material for any other purpose. 3. The restricted waiver of copyright is not transferable and may be withdrawn in the case of breach of any of these conditions. 2

3 PURPOSE PROCEDURE The purpose of these activities is to use spreadsheet application Microsoft Excel to make predictions about weekly growth of seeds germinated in different growing conditions, and to generate a chart or graph to display the predictions. Select and open Microsoft Excel. When the software has begun, a new blank spreadsheet will be visible on screen. Setting up the spreadsheet The first cell, that is A1, will be highlighted, indicating you can enter information into the cell. As this will be the heading for the spreadsheet type the heading, for example, Seed germination. When you have finished typing, press the Enter key on the keyboard to indicate you have finished. Move the cursor into cell B3. Type the column heading Normal light. Press the Tab key on the keyboard to move to the next cell. Type 24 hour light and press Tab. Type Shaded light and press Enter. Use the mouse to click in the cell A4. The cell will be highlighted ready to enter your information. Type the row heading, Week 1. Press Enter to move to the next row and type Week 2. Continue adding the row heading for week 3, week 4 and week 5. In the cell A9, type the row heading Average weekly growth. You will notice the heading Average weekly growth appears to stretch across more than one column. This is because there is no information at this stage in the second column. When you enter information in the column, some of the text will no longer be visible. For example, place the cursor in the cell B9 and type zero (0) and press Enter. Now only part of the heading Average weekly growth is visible (delete the zero before continuing to the next step). To have all the heading visible, you will need to adjust the width of the column. To change the column width, move the cursor to the top row where the cell letters are located. Move the cursor onto the line separating the first two columns, that is A and B. 3

4 Entering data When the cursor changes shape, click and hold down the mouse button. As you move the mouse to the right, the width of the column will increase. You now need to add the information about the growth rate of the seeds over the five-week period. For this example, you should simply enter mythical data. Place the cursor in the cell indicating the growth of the seeds in normal light in week one. This is cell B4. Type a number and press Enter on the keyboard. Type the information for the seeds in week 2, week 3, week 4 and week 5. Place the cursor in the cell indicating the seed s growth rate in 24 hour light in week 1. Type some information. Type the information for the seeds in week 2, week 3, week 4 and week 5. Type the information for the seed s growth in shaded light over the five weeks. Performing calculations To work out the average weekly growth over the five weeks, you need to perform a calculation. Calculations are based on formulas entered into individual cells. To allow the spreadsheet to determine if you have entered a formula or simply a number, the equal sign (=) is used. For example, =B5 is handled as a calculation whereas B5 is handled as text. 4

5 Common symbols in a formula + (plus) adds numbers together. For example =C4+C5 adds the value in the cells C4 and C5 and returns the total. - (minus) subtracts numbers. For example =C4-C5-D3 subtracts the value in the cells C5 and D3 from the value in C4 and returns the total. / (divided by) divides numbers. For example =C4/C5 divides the value in the cell C4 by the value in C5 and returns the total. * (multiply) multiplies numbers. For example =C4*C5 multiplies the value in the cell C4 by the value in cell C5 and returns the total. Creating a formula Place the cursor in the cell B9. This cell will calculate the average growth in normal light over the five weeks. To indicate the cell is to contain a calculation or formula (the total time from cells B4 to B8), enter the equal (=) sign. To find the total, enter the calculation: =B4+B5+B6+B7+B8 When you have finished typing, press Enter and the calculation will be performed. This gives you the total growth for the five weeks. To find the average, you will need to modify the formula. To modify the formula, click on the cell to be changed, B9. You do not actually change the information in the cell but in the formula bar at the top of the spreadsheet. Any changes you make in the formula bar are automatically entered into the cell. To edit the formula, click the mouse in the formula bar. Change the formula to =(B4+B5+B6+B7+B8)/5 By adding the brackets you have indicated you want the total for the cells. By adding the /5 (divided by 5) you have indicated you want the total of the brackets divided by 5. The average will be displayed in the cell B9. Place the cursor in the cell C9. Type the formula to calculate the average for this column: =(C4+C5+C6+C7+C8)/5 Place the cursor in the cell D9 ready to calculate the average. However, create a new formula to calculate the average. You could use the formula =D4+D5+D6+D7+D8 as you did for the other growth rates. However, a more efficient way is to create a formula to add the totals automatically. You can use the formula: =sum(d4:d8)/5 The formula asks for the sum of all cells between D4 and D8. The semicolon between D4 and D8 indicates it is a range of cells. Press Enter to have the calculation performed. 5

6 Generating a chart or graph You now have enough information to generate a chart or graph. To create a chart or graph, you must indicate the information to be included. This is done by highlighting the information in the spreadsheet. Place the cursor in the cell A4. Hold down the mouse button and drag the cursor to the cell D9. All the information in these cells is now highlighted and will be included in the chart or graph. Locate and select the Chart Wizard button on the main menu bar. The Chart Wizard will open on screen. 6

7 The Chart type window on the left allows you to select the type of chart to create. Clicking on a Chart type will change the Chart Sub-type options. The Chart Sub-types can be selected by clicking on the appropriate chart in the window on the right. In the example above, a Column chart is selected. To view the column chart to be created from the data in the spreadsheet, locate the button Press and Hold to View Sample. Use the mouse to click on this button but continue to hold down the mouse button to have the column chart displayed. Select the Next Wizard window. button at the bottom of the Chart The next window allows you to begin to manipulate the method of displaying the information in the chart. You can experiment further with these options; however, as you only need a simple chart, select Finish. The chart will be created and displayed in the spreadsheet. When the chart is inserted into the spreadsheet, a new menu bar will also appear. This menu provides shortcuts to the main features found in the Chart Wizard. The menu allows you to quickly change the type of chart, and to format the chart by selecting fonts and colours or the way the information is displayed. You can now edit the information contained in your spreadsheet and it will automatically be reflected in the chart. Moving and resizing a chart To move the chart to another position in the spreadsheet, click on the chart and hold down the mouse button. Drag the chart to the new location and release the mouse button. To change the size of the chart, click on the chart to make it active. The chart handles will appear in the corners of chart. Place the cursor on one of the handles. While holding down the mouse button drag, the handle to a new location on the screen. 7

8 As the cursor moves, the chart size will be increased or reduced according to the movement of the cursor. Using the spreadsheet to make predictions The students experiment will continue for another five weeks. Based on the information collected for the first five week, students can use the spreadsheet to predict the seed s growth over the next five weeks. To do this, set up the spreadsheet with the appropriate row headings, that is weeks 6 to week 10. Place the cursor in the row A11 and type the heading Predicted growth. Place the cursor in the cell A12 and type Week 6. Type the row headings for week 7, week 8, week 9 and week 10. Place the cursor in the cell B12. This cell will contain the predicted height for the seed s growth in week 6. The prediction is based on the average of the previous growth rate. Type the cell reference B9; this is the average for weeks one to five. You need to add the average to the height at the end of week five. The formula should be: =B9+B8 (and press Enter). Type the formula for week 7 s prediction. Take the information in the cell B9 and add it to the information in cell B12. The formula will be =B9+B12 (and press Enter). Repeat for week 8 (B9+B13), week 9 (B9+B14) and week 10 (B9+B15), adding the average growth to the predicted height from the previous week. Create the predictions for the seeds in 24 hour and shaded light, adding the average height for these conditions to the new predicted height. To graph the predictions, place the cursor in the cell A12. Highlight the cells to be included in the chart or graph by holding down the mouse button and drag the cursor to the cell D15. Select the Chart Wizard button from the main menu bar and select the chart type required. 8

9 To view the column chart to be created, locate the button Press and Hold to View Sample. Use the mouse to click on this button but continue to hold down the mouse button to have the chart displayed. Select the Finish button to have the new chart inserted into the spreadsheet. Real growth chart Normal Light 24 hour light Shaded light Week 1 Week 2 Week 3 Week 4 Week 5 Predicted growth chart Normal Light 24 hour light Shaded light Week 6 Week 7 Week 8 Week 9 Week 10 9