Order, Order Again!
Key words: Integer, positive, negative, plus, minus.
Read −6 as "negative six".
Objectives
• Order negative numbers.
Instructions for the teacher:
The purpose of this activity is to generate sets of integers for
pupils to put in order.
Lists of random numbers can be generated automatically. They
can be stored and viewed. Pupils can then attempt to order the
lists. When they are ready the calculator can sort the list to
validate the pupil’s attempt.
Note: this activity uses the same techniques as ‘Ordering
Decimals’ and makes a good follow on activity.
KS3 Framework
page ref: 48
Press STAT
Choose 1:Edit to show the list editor.
Use the up cursor to highlight the L1 header
Press ▲
Now enter the command to generate the sequence of random
numbers.
Press MATH
Press ► ► ► to select the PRB menu
Choose 5:randInt
Type (-) 10 , 10 , 10 )
Use the left and right cursor to check that you have entered
this:
L1 = randInt(−10, 10, 10)
Press ENTER
This has generated a random collection of 10 numbers between
−10 and 10. The first two numbers give the range. The third
number gives the number generated.
Use the up and down cursor keys ▲ and ▼ to view the whole
list.
Students can now work on their list.
When they are ready the calculator can order the list for you.
Press 2nd STAT to show the LIST menu
Press ► to select the OPS menu
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Choose 1 (SortA) meaning sort in ascending order
Press 2nd 1 to sort list L1
Press ENTER
Press STAT
Choose 1:Edit
Again: Use the up and down cursor keys ▲ and ▼ to view the
whole list.
Once you feel confident with the procedure, it is possible to
vary the sequence in lots of different ways. Notably you can
change the range of the sequence:
e.g. L1 = randInt(−20, 20, 10)
This generates a sequence between −20 and 20 with 10
numbers.
e.g. L1 = randInt(−1000, 1000, 20)
This generates a sequence between −1000 and 1000 with 20
numbers.
The random number generator needs a seed to start the
sequence it generates. To make sure that different sequences
are generated you can change the seed. To do this, enter any
number into rand. (For example: change the seed to 0.5)
Press 2nd MODE (for QUIT) to get the main screen
Press 0.5
Press STO→
Press MATH
Press ► ► ► to select the PRB menu
Choose 1:rand
Press ENTER
Answers to student activity sheet.
1. –10, –6, –4, 2, 5, 7, 10
2. –28, –24, –15, 12, 26, 27, 30
3. –154, –166, –121, –75, –41, 53, 199
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Order, Order Again!
First: Reset your TI 83-Plus
• Press 2nd + to get MEM
• Choose 7 (Reset…)
• Choose 1 (All Ram…)
• Choose 2 (Reset)
This activity will give you a list of negative and positive numbers.
Your job is to put them in order.
You can use your calculator to check if you have got it right.
The first three questions will help you practice without the calculator.
1.
Look at the list of negative and positive numbers in the list L1.
Write them in order of size, smallest first.
2.
Now write this list in order of size:
3.
Now write this list in order of size:
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4.
Now you can make lists of your own.
Press STAT
Choose 1:Edit to show the list editor
Press ▲ Use the up cursor to highlight the L1
Press MATH
Press ► ► ► to select the PRB menu
Choose 5:randInt
Type (-) 10 , 10 , 10 )
Press ENTER
There are 10 numbers in your list.
Use the up and down cursor keys ▲ and ▼ to see them all.
Write down the list in order of size, smallest first.
5.
Now sort the list on the calculator
Press 2nd STAT to show the LIST menu
Press ► to select the OPS menu
Choose 1:SortA
Press 2nd 1 to sort list L1
Press ENTER
Press STAT
Choose 1:Edit
Check that your answers are the same.
6.
Repeat steps 4 and 5 again, but change this line:
Type (-) 10 , 10 , 10 ), to:
(a)
(b)
(c)
(d)
7.
Type (-) 20 , 20 , 10 )
Type (-) 100 , 100 , 10 )
Type (-) 100 , 100 , 20 )
Type (-) 1000 , 1000 , 20 )
there will be 20 numbers in the last two lists.
Experiment with different start and finish numbers. Experiment with different
length lists. Record the most interesting list you generate. Write the numbers in
order.
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