## Math 2 Enrichment Answers and Notes

1i) d.

1g) This game depends not only on knowing doubles facts but also on remembering the positions of the cards that have been turned over.

1f) A doubles fact is a single-digit number added to itself.

2i) b.

2g) Students can count forward or backward the given number of hours on the clock faces.

2f) When your child draws a time to the hour, the minute or "big" hand should point exactly to 12 and the hour or "small" hand to the hour you discuss.

3i) a.

3g) The following are examples of straight-sided shapes:

3f) For example, the face of an analog clock is a circle, and the surface of a door or table is a rectangle.

4i) c.

4g) A some, some more story is about addition. A some, some went away story is about subtraction.

4f) 1 + 2 = 3;

2 + 2 = 4;

3 + 2 = 5;

4 + 2 = 6;

5 + 2 = 7;

6 + 2 = 8;

7 + 2 = 9;

8 + 2 = 10;

9 + 2 = 11

5i) b.

5g) Answers may vary, depending on how students print the letters. Possible answers:
D, E, F, H, I, K, L, M, N, P, R, T, and Y have vertical line segments.
A, B, E, F, G, H, I, J, L, R, T, and Z have horizontal line segments.
A, K, M, N, Q, V, W, X, Y, and Z have oblique line segments.

5f)

6i) c.

6g) Ways to make ten are 0 + 10, 1 + 9, 2 + 8, 3 + 7, 4 + 6, 5 + 5, 6 + 4, 7 + 3, 8 + 2, 9 + 1, and 10 + 0.

6f) Your child may use addition facts to find how many more are needed.

7i) c.

7g) Students should be able to tell how much money there is altogether after trading pennies for dimes.

7f) When your child is finished, suggest that he or she count the coins and tell you how much money he or she found.

8i) a.

8g) Students can return the papers and check each other's measurements.

8f) When a measurement falls between two whole inches, your child should determine which whole inch it is closer to and round the measurement accordingly.

9i) b.

9g) Students should begin by comparing the digits in the tens' place.

9f) In this case, from least to greatest means "from youngest to oldest."

10i) d.

10g) Some students may not be able to add past 18.

10f) Your child should look for sums of 10 and doubles when adding more than two numbers.

11i) a.

11f) The greatest sum possible is 96¢.

12i) c.

12g) Examples of mixed numbers that may be modeled are 1 1/2, 3 1/4, and 2 5/8.

12f) Your child should express the idea that a mixed number has two parts: a whole-number part and a fraction part.

13i) a.

13g) for example, 10 minutes past 3 or 3:10

13f) Going clockwise (to the right), your child should count 5 at 1, 10 at 2, 15 at 3, and so on, through 60 at 12.

14i) b.

14g) The tally marks should be in groups of five.

14f) Remind your child that a bar graph is a quick and easy way to compare data.

15i) c.

15g) Two-digit numbers less than 50 range from 10 through 49. Two-digit numbers greater than 50 range from 51 through 99.

15f) Your child may at first need to guess and then check several of his or her numbers for each one you name. As your child becomes more adept at adding to 100, the guesses will become fewer and more accurate.

16i) d.

16g) Here are the fact family subtraction facts for each addition fact:

5 + 3 = 8: 8 - 5 = 3, 8 - 3 = 5

6 + 3 = 9: 9 - 6 = 3, 9 - 3 = 6

8 + 3 = 11: 11 - 8 = 3, 11 - 3 = 8

8 + 6 = 14: 14 - 8 = 6, 14 - 6 = 8

7 + 4 = 11: 11 - 4 = 7, 11 - 7 = 4

8 + 4 = 12: 12 - 8 = 4, 12 - 4 = 8

7 + 5 = 12: 12 - 7 = 5, 12 - 5 = 7

8 + 5 = 13: 13 - 8 = 5, 13 - 5 = 8

16f) Your child should be able to use addition and subtraction fact families to find each answer.

17i) b.

17f) For example, an audiocassette is about 10 centimeters long, and a telephone directory is about 20 centimeters wide.

18i) a.

18f) Encourage your child to begin by counting the coins of the greatest value, then the ones of lesser and lesser values.

19i) d.

19g) halves: eight right angles; fourths: sixteen right angles; eighths: thirty-two right angles

19f) A right angle is a square corner or an angle that measures 90°.

20i) d.

20g) For example, June 1, 1993, is expressed 6/1/93 in digits.

20f) A full date consists of the spelled-out month, the date, and four-digit year, with a comma between the date and the year. Slashes are used to separate the month, date, and year when using digits (for example, May 7, 1953, and 5/7/53).