4.7 Digital clocks

Mathematics

Bonny and tommy at the sea

Educator section

Memorandum

It will probably only be learners in the first group who will progress as far as this module. Do not discourage learners who want to do this module. Even if they can only do a few of the activities they must be given the opportunity to do so. This must be handled carefully so that learners are not discouraged or feel inferior towards other learners. Neither must they develop negative attitudes towards Mathematics.

• Number concept to 2 000
• Operations: Consolidation and reinforcement of all the operations in previous modules.

A considerable amount of advanced and enrichment work is included and the educator must be familiar with each activity before the learners are expected to complete them.

In Module 8 number concept is extended to 2 000 . All operations are revised and consolidated. Several enrichment and challenging activities are included in this module and should only be given to learners who can manage them and who enjoy challenges. This selection process must be handled carefully and the other learners must not be discouraged or feel inferior towards other learners or the subject Mathematics.

A thorough discussion and explanation of the map on p. 3 as well as the table of distances on p. 4 should help learners complete these worksheets.

Number concept is extended to 2 000.

This is consolidation of the operations as in the previous modules. It offers an opportunity to identify problem areas.

These are to determine to what extent the learners’ logical thought processes have developed and to test and consolidate the basic work.

Telling the time on digital clocks/watches should only be done with learners who have mastered the telling of time on ordinary (analogue) clocks/watches. They need much practice in telling the time on ordinary clocks/watches and the corresponding time on digital clocks/watches before completing the worksheets.

Give the learners the opportunity to do these problems without help so that their progress can be determined.

Show examples and discuss ethnic patterns with the learners. Encourage them to bring examples to school and to share these with the class.

Use this for assessment purposes.

This is enrichment work and the educator should study this work first and then decide which of these worksheets should be used for which learners.

All learners who have progressed to Module 8 should be able to complete these worksheets with ease.

Do this activity practically in the classroom and let several learners explain what they see in front of them when walking behind someone. Let three learners stand next to one another and let the other learners stand in front of them. They must walk around the three standing in a line and observe them from behind so that they can discover that the order from left to right has changed.

Not much explanation is needed here as this activity is similar to the one where they used the table of distances.

Leaner section

Content

Activity: digital clocks [lo 1.8, lo 4.1]

Bonny and Tommy can tell the time on an ordinary clock (analogue clock) but now we must see whether they can tell the time on a digital clock.

The digital clock shows the full 24 hours of day. It ranges from midnight to midnight the following day. That is the reason why the letters a.m. (before noon) and p.m. (after noon) are not used. (anti-meridian, post-meridian).

• On the ordinary clock the time is written as: 1 a.m . or 1 p.m .
• On the digital clock the time is shown as: 1:00 and 13:00 .
• The hours after 12 o’clock, midday, are counted on. They don’t begin from 1 o’clock again but from 13 hours.
• The minutes are written after the colon and means so many minutes after the hour has past.

These are times between midnight and 12 o’clock in the afternoon :

• What is the time?

• Write the correct time on the digital clocks:

• Now we are going to work with the hours after twelve o’ clock in the afternoon .
• We write the hours like this:

13:00 14:00 15:00 16:00 17:00 18:00

19:00 20:00 21:00 22:00 23:00 24:00

• What is the time on the ordinary clock?

Use any method to solve the problems.

• We left Kimberley at 6:00 and arrived in Cape Town at 16:45. We spent an hour on the way to fill up on petrol and to stretch our legs. How long did we actually travel ?

• School begins at 8:00 in the morning and finishes at 14:00. Bonny and Tommy played tennis until 16:15. How much longer than usual was their school day?
• Last year dad caught a fish of 8 kg. Tommy caught a fish of 3,25 kg. What was the difference in mass of the two fish?
  • Later Bonny caught a fish of 1,50 kg. What was the total mass of their catch?
  • An octopus has eight arms. How many arms have 20 octopuses altogether?
  • A starfish has five arms. I saw 75 such arms in the sea. How many starfish were there?

Assessment

Learning Outcome 1: The learner will be able to recognise, describe and represent numbers and their relationships, and to count, estimate, calculate and check with competence and confidence in solving problems.

Assessment Standard 1.8: We know this when the learner can perform calculations, using appropriate symbols, to solve problems;

Learning Outcome 4: The learner will be able to use appropriate measuring units, instruments and formulae in a variety of contexts.

Assessment Standard 4.1: We know this when the learner reads and writes analogue and digital clock time in terms of hours, half-hours, quarters of an hour and minutes.