1. Surprised Visitor T. Trimpe 2006 http://sciencespot.net/ Case #5

2. The clock in the courthouse ahead of Max showed six o'clock. As it began chiming, he noticed a tall man with a briefcase walking towards him. The man turned around, looked at the clock, and then quickened his steps. He took an envelope and dropped it in a mailbox as he continued on. Max moved faster, too. Miss Fritz had invited him for dinner. He didn't want to be late. "I'm glad you could come," Harborville's oldest music teacher said. "I've made a lovely salad for us." She gestured Max to a chair. "Good thing I prepared ahead. A surprise visitor just left." "Who visited?" Max asked. "A teacher from Harborville's School for the Deaf,” she replied. “He was totally deaf himself; poor man, but he could read lips perfectly. He had the loveliest penmanship when he wanted to tell me something." Source: http://kids.mysterynet.com/quicksolve/

3. "Why was he here?" he asked. She said, "Well, evidently the school is low on funds. I was glad to help out. I had just cashed my social security check so I was able to give him five hundred dollars." "Did he just leave?” he asked. “Was he a tall man with a brief case?" "Yes," she replied. "We'd better phone the police. I think that man was a phony. I know for sure he wasn't totally deaf." How did Max figure it out?

4. The clock was behind the man as he was walking, so he could not have seen it. He turned around at the sound of the chimes, so he obviously heard them.

5. 〉 Why is organizing data an important science skill? 〉 How do scientists handle very large and very small numbers? 〉 How can you tell the precision of a measurement?

6. Imagine your teacher asked you to study how the addition of different amounts of fertilizer affects plant heights. In your experiment, you collect the data shown in the table below. Use this data to answer the following questions.

7. 1. Which amount of fertilizer produced the tallest plants? 2. Which amount of fertilizer produced the smallest plants? 3. Plot the data on a grid like the one below. 4. Describe the overall trend when more fertilizer is used to grow plants.

8.  Why is organizing data an important science skill?  Because scientists use written reports and oral presentations to share their results, organizing and presenting data are important science skills.

9.  Line graphs are best for continuous change.  dependent variable: values depend on what happens in the experiment  Plotted on the y-axis  independent variable: values are set before the experiment takes place  Plotted on the x-axis

11.  Bar graphs compare items.  A bar graph is useful for comparing similar data for several individual items or events.  A bar graph can make clearer how large or small the differences in individual values are.

13.  Pie graphs show the parts of a whole.  A pie graph is ideal for displaying data that are parts of a whole.  Data in a pie chart is presented as a percent. Composition of a Winter Jacket

14. 〉 How do scientists handle very large and very small numbers? 〉 To reduce the number of zeros in very big and very small numbers, you can express the values as simple numbers multiplied by a power of 10, a method called scientific notation.  scientific notation: a method of expressing a quantity as a number multiplied by 10 to the appropriate power

15.  Some powers of 10 and their decimal equivalents are shown below. 10 3 = 1,000 10 2 = 100 10 1 = 10 10 0 = 1 10 -1 = 0.1 10 -2 = 0.01 10 -3 = 0.001

16.  Use scientific notation to make calculations.  When you use scientific notation in calculations, you follow the math rules for powers of 10.  When you multiply two values in scientific notation, you add the powers of 10.  When you divide, you subtract the powers of 10.

17. Writing Scientific Notation The adult human heart pumps about 18,000 L of blood each day. Write this value in scientific notation. 1. List the given and unknown values. Given: volume, V = 18,000 L Unknown: volume, V = ?  10 ? L

18. 2. Write the form for scientific notation. V = ?  10 ? L 3. Insert the known values into the form, and solve. Find the largest power of 10 that will divide into the known value and leave one digit before the decimal point. You get 1.8 if you divide 10,000 into 18,000 L. 18,000 L can be written as (1.8  10,000) L

19. Then, write 10,000 as a power of 10. 10,000 = 10 4 18,000 L can be written as 1.8  10 4 L V = 1.8  10 4 L

20. Using Scientific Notation Your county plans to buy a rectangular tract of land measuring 5.36 x 10 3 m by 1.38 x 10 4 m to establish a nature preserve. What is the area of this tract in square meters? 1. List the given and unknown values. Given: length (l )= 1.38  10 4 m width (w) = 5.36  10 3 m Unknown: area (A) = ? m 2

21. 2. Write the equation for area. A = l  w 3. Insert the known values into the equation, and solve. A = (1.38  10 4 m) (5.36  10 3 m) Regroup the values and units as follows. A = (1.38  5.36) (10 4  10 3 ) (m  m) When multiplying, add the powers of 10. A = (1.38  5.35) (10 4+3 ) (m  m) A = 7.3968  10 7 m 2 A = 7.40  10 7 m 2

22. 〉 How can you tell the precision of a measurement? 〉 Scientists use significant figures to show the precision of a measured quantity.  precision: the exactness of a measurement  significant figure: a prescribed decimal place that determines the amount of rounding off to be done based on the precision of the measurement

23.  Precision differs from accuracy.  accuracy: a description of how close a measurement is to the true value of the quantity measured

26.  Round your answers to the correct significant figures.  When you use measurements in calculations, the answer is only as precise as the least precise measurement used in the calculation.  The measurement with the fewest significant figures determines the number of significant figures that can be used in the answer.  Sig Fig video example for visual reference if you have trouble.

27.  Read from the left and start counting sig figs when you encounter the first non-zero digit  Rule 1  All non zero numbers are significant (meaning they count as sig figs)  613 has three sig figs  123456 has 6 six figs

28.  Rule 2  Zeros located between non-zero digits are significant (they count)  5004 has four sig figs  602 has three sig figs  60000000000000000000000002 has 26 sig figs

29.  Rule 3  Trailing zeros (those at the end) are significant only if the number contains a decimal point; otherwise they are insignificant (they don’t count)  5.640 has four sig figs  120000. has six sig figs  120000 has two sig figs

30.  Rule 4  Zeros to left of the first nonzero digit are insignificant (they don’t count); they are only placeholders!  0.000456 has 3 sig figs  0.052 has 2 sig figs  0.000000000000052 has 2 sig figs!

31.  The number of sig figs in the final calculated value will be the same as that the fewest number of sig figs in the calculation.  Example Next slide

32. Significant Figures Calculate the volume of a room that is 3.125 m high, 4.25 m wide, and 5.75 m long. Write the answer with the correct number of significant figures. 1. List the given and unknown values. Given: length, l = 5.75 m width, w = 4.25 m height, h = 3.125 m Unknown: volume, V = ? m 3

33. 2. Write the equation for volume. V = l  w  h 3. Insert the known values into the equation, and solve. V = 5.75 m  4.25 m  3.125 m V = 76.3671875 m 3 The answer should have three significant figures, because the value with the smallest number of significant figures has three significant figures. V = 76.4 m 3