400
“What’s My Rule?” with Numbers
Objective
To help children identify function rules and
generate numbers that follow those rules.
Whole Group
Small Group
Partners
Center
Key Concepts and Skills
•
•
•
•
Apply addition- and subtraction-based rules. [Operations and Computation Goal 1]
Explore the difference between addition and subtraction rules. [Operations and Computation Goal 2]
Use related pairs of numbers to identify function rules. [Patterns, Functions, and Algebra Goal 1]
Use rules to determine missing numbers in a number pair. [Patterns, Functions, and Algebra Goal 1]
Terms to Use function machine, rule
Materials chalkboard; chalk; eraser
A
Core Activities
► Solving “What’s My Rule?” with Numbers
Rule
Draw a function machine and an in/out chart on the board. Review the function machine
by having children apply a simple rule, such as “Add 3” to compute several out numbers.
After children have worked with several examples, explain that you will show them
some in and out numbers, and they should try to figure out what the rule on the
function machine is. Think of a rule and write at least three in and out pairs that follow
the rule. (The accompanying diagram shows examples for the rule “Add 2.”) Write a
question mark in the rule space on your function machine and on your in/out chart. Ask:
What’s my rule? After gathering responses, write the correct rule and have children
share and discuss how they figured out your rule. Then write another in number and
ask children what the out number should be. Finally, write an out number and ask
children what the in number should be.
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in
2
out
4
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5
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Provide a set of in and out pairs that follow a different rule, and have children use them
to figure out your rule. Also have them apply the rule to figure out missing in and out
numbers. Repeat using both addition and subtraction rules as long as time and interest
permit. Gradually increase the difficulty by using more challenging rules, such as
“Add 10.” Also begin to use higher in numbers.
► Using the Hour-Hand Clock (Revisit Activity 8 3, p. 384)
Call out several approximate times (a little past 10 o’clock, half past 4 o’clock, exactly
8 o’clock, and so on) for children to show on their hour-hand clocks.
B
Teaching Options
EXTRA PRACTICE
► Solving “What’s My Rule?” with a Partner
(Math Masters, p. 58)
Partners can solve “What’s My Rule?” problems in the Math Center. One child records
pairs of in and out numbers on a slate or a copy of Math Masters, page 58. The other
child uses the pairs of numbers to guess the rule.
EXTRA PRACTICE
► Using “What’s My Rule?” for Facts Practice
Provide children with “What’s My Rule?” problems that use +0, – 0, +1, –1, +2, and –2
as rules. This will help them internalize the patterns for adding and subtracting these
small numbers, which will help them build fluency for these facts.
Ongoing
Assessment:
Recognizing Student
Achievement
Use “What’s My Rule?” with
Numbers to assess children’s
ability to complete a number pair
by applying a rule. Children are
making adequate progress if
they can apply simple addition
and subtraction rules to complete
a number pair.
[Patterns, Functions, and
Algebra Goal 1]
MATHEMATICS IN THE BLOCK CENTER
► Building and Using a Function Machine
Children can build a function machine with blocks, add a rule, and then use small
blocks or interconnecting links to represent the in and out numbers.
401 Activity 8 10 “What’s My Rule?” with Numbers
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