Optical Illusions (1)

Transcription

1 Optical Illusions (1) In the picture, the line segments at the top and at the bottom are the same length, but the line at the top looks longer. Let s investigate this optical illusion. 1. Draw two horizontal line segments, each 2 cm long, between each pair of lines, one near the top of the picture and one near the bottom. Which pair of slanted lines makes the best optical illusion? a) b) c) 2. Draw the same two line segments as in Question 1, but use a different color. Which pair of lines makes the best optical illusion? Does color matter in this optical illusion? a) b) c) 3. Draw the same two line segments as in Question 1, but make them very thick. Which pair of lines makes the best optical illusion? Does thickness matter in this optical illusion? a) b) c) G-61

2 Optical Illusions (2) 4. This time make two line segments 4 cm long. Which pair of lines makes the best optical illusion? Does the length of the horizontal line segment matter in this optical illusion? a) b) c) 5. Draw the same two line segments as in Question 1 in each picture. Which picture makes the best optical illusion? Does background matter in this optical illusion? a) b) c) G-62

3 Trip Map CALIFORNIA Lake Tahoe 305 km 291 km NEVADA YOSEMITE NATIONAL PARK Lake Mono San Francisco KINGS CANYON NATIONAL PARK 614 km SEQUOIA NATIONAL FOREST Las Vegas 434 km DEATH VALLEY NATIONAL PARK 426 km MOJAVE NATIONAL PRESERVE Los Angeles G-63

4 Pentamino G-64

5 Make Your Own Clock G-65

6 Telling Time (Half and Quarter Hours) (1) When the minute hand (the long hand) travels from the 12 around the clock until it hits the 12 again, one hour has passed. quarter past half past quarter to 1. In each question, shade in the space from the 12 to the minute hand as above. Then indicate whether the minute hand is half past, quarter past, or quarter to the hour. a) b) c) d) half past e) f) g) h) 2. What time is it? Circle the correct answer. a) b) c) d) quarter to 8 or 7 quarter to 10 or 9 quarter to 10 or 11 quarter to 1 or 2 e) f) g) h) quarter past 2 or 3 quarter past 4 or 5 quarter past 5 or 6 quarter past 10 or 9 G-66

7 Telling Time (Half and Quarter Hours) (2) 10:30 is half way 10:15 is a quarter of the 10:45 is three quarters from 10:00 to 11:00 way from 10:00 to 11:00 of the way from 10:00 to 11:00 3. Write where the minute hand is. Draw the hour hand, and write the time. a) The minute hand is b) The minute hand is three quarters of the way from 1:00 to 2:00. The time is 1:45. from 1:00 to 2:00. c) The minute hand is d) The minute hand is from 4:00 to 5:00. from 2:00 to 3:00. e) The minute hand is f) The minute hand is from 8:00 to 9:00. g) The minute hand is from 10:00 to 11:00. from 7:00 to 8:00. h) The minute hand is from 10:00 to 11:00. G-67

8 Telling Time in Two Ways 1. Shade in the space from the 12 to the minute hand, so that the shaded part is less than half of the circle. a) b) c) d) e) f) g) h) 2. Which hour is the hour hand closer to? Circle the answer. a) 11 or 12 b) 10 or 11 c) 6 or 7 d) 8 or 9 e) 4 or 5 f) 12 or 1 g) 3 or 4 h) 2 or 3 When it is less than half an hour to the next hour, we can tell time two ways: 40 minutes past 5 20 minutes to 6 3. Tell the time in two ways. a) b) minutes past minutes to minutes past minutes to G-68

9 Telling Time (Review) (1) 1. How many minutes is it past the hour? Count by 5s around the clock, filling in the boxes as you go. 5 a) 10 b) c) 15 : 15 : : d) e) f) : : : The hour hand (the short hand) moves in a clockwise direction. When the hand is between 7 and 8 the hour is still What is the hour? a) b) c) d) 1 : : : : e) f) g) h) : : : : G-69

10 Telling Time (Review) (2) 3. What time does the analog clock show? Write the answer in numbers and in words. a) b) 12 : 30 : Thirty minutes after twelve c) d) : : 4. What time does the digital clock show? Write the answer in words and draw the hands on an analog clock. a) b) 5. Draw the hands on each clock to show the time. a) 4:45 b) 8:15 c) 2:10 G-70

11 Clocks G-71

12 Telling Time (The Second Hand) The second hand is longer and thinner than both the minute and hour hands. The second hand is read just like the minute hand. The exact time, written digitally and including seconds, is: minute hand second hand hours minutes seconds hour hand 1. Under each clock, write the time digitally. a) b) c) d) e) f) 2. Draw the hands on the analog clock to show the time. a) 3 : 50 : 35 b) 7 : 02 : 23 c) 9 : 15 : 05 G-72

13 The 24-Hour Clock 1. Complete the following tables using the pattern. 12-hr Clock 24-hr Clock 12-hr Clock 24-hr Clock 12-hr Clock 24-hr Clock 12:00 a.m. 00:00 9:00 a.m. 09:00 5:00 p.m. 17:00 1:00 a.m. 01:00 10:00 a.m. 6:00 p.m. 2:00 a.m. 02:00 12:00 p.m. 12:00 1 p.m. 13:00 2. a) What number must you add to 1 p.m. to change it to 24-hour notation? b) List three other times that change this way: 3. For each time in 12-hour notation, write the corresponding time in 24-hour notation. (Only look at the chart above if you need help!) a) 5:00 a.m. = b) 11:00 p.m. = c) 6:00 p.m. = d) 3:00 p.m. = e) 8:00 p.m. = f) 12:00 a.m. = g) 12:00 p.m. = h) 9:00 p.m. = BONUS 7:25 p.m. = 4. For each time in 24-hour notation, write the corresponding time in 12-hour notation. a) 07:00 = b) 15:00 = c) 13:00 = d) 00:00 = e) 18:00 = f) 17:00 = 5. Complete the table to show when David left each exhibit in a museum (using 24-hour notation). Front Desk Dinosaurs Reptiles Lunch Ancient Egypt Bat Cave Time Spent 1 hour 2 hour 30 minutes 1 hour 30 minutes Time Finished 10:30 6. Describe any differences between the way time is written in 24-hour and 12-hour notation a) in the morning (a.m.). b) in the afternoon or evening (p.m.). G-73