Display the Number of Math Mice Features Master.
Tell students you are going to add ears to your Math
Mouse. Draw two ears on the display mouse. Title
the last column of the data table on the Master
"Number of Ears." Have student pairs complete the
Mouse Ears page in the Student Activity Book. They
will determine the amount of ears on one to six mice
and write number sentences to describe each situation.
Draw students' attention to the first row of the
table. One mouse has 2 ears. The number sentence is
2 = 2.
- How is this number sentence different from the
ones we have been writing in this lesson? (The
other ones repeat numbers. For example, 3 mice
would have 6 ears. The number sentence is 2 + 2
+ 2 = 6.)
- Is 2 = 2 a true number sentence? Why or why not?
(It is a true number sentence because the quantities
on either side of the equal sign are the same.)
- How does 2 = 2 describe this situation? (There is
no repeated addition. 2 ears on one mouse is just
2.)
Upon completion, ask student volunteers to fill in
the Number of Ears column on the data table on the
displayed Master. Ask several to share their number
sentences with the class.
- What is the number sentence for the number of
ears on 5 mice? (2 + 2 + 2 + 2 + 2 = 10.)
- What do the twos represent in the number sentence?
(There are 2 ears on each mouse.)
- How did you know how many numbers to add in
your number sentence? (Possible response: There
were five mice, each with two ears, so I had to
add 2 five times.)
- Now that you have a number sentence for 5 mice,
is it easy to write a number sentence for 6 mice?
(Yes. For the number of ears, I just added one
more 2 to my number sentence and I added 2 to
the answer.
10 + 2 = 12.)
Next, tell students to think about ten Math Mice and
write 10 on the Number of Mice column on the data
table. Assign each student pair one of the columns
on the data table and ask them to find the information
for 10 mice. There are seven columns including
the Number of Ears column. They should write a
number sentence describing the situation. For example,
a pair assigned to the Number of Gray Lines for
Body column would write 3 + 3 + 3 + 3 + 3 + 3 + 3
+ 3 + 3 + 3 = 30. Students may use any strategy or
tool to help them solve the problem.
Ask questions such as the following:
- How did you know what numbers to add to find the
answer? (Possible response: For Number of
Black Whiskers, I looked at the number of
whiskers for one mouse, 6, and I added that number
10 times for 10 mice. It was 6 + 6 + 6 + 6 + 6
+ 6 + 6 + 6 + 6 + 6 = 60.)
- What does each number in your number sentence
represent? (Possible response: Each 6 shows that
there are 6 whiskers on a mouse.)
- How many [sixes] are in your number sentence?
Why? (Possible response: There are 10 sixes
because there are 10 mice.)
To provide a more challenging task for some students, give
them a repeated subtraction situation. For example, on an
empty row, write 24 under the Number of Blue Dots for Eyes
column and have student pairs fill in the number of mice on
the chart. Then have them complete the row for the other
features.
Assign the Squid Squares pages in the Student
Activity Book to assess students' abilities to solve
problems involving repeated addition or subtraction
concepts. Make sure students see that each squid eye
is made of three circles.
Use the Squid Squares pages with Feedback Box in the
Student Activity Book to assess students' abilities to:
represent repeated addition and repeated situations using
counters and drawings [E2]; solve repeated addition and
repeated subtraction problems using drawings, skip
counting, and invented strategies [E3]; know the problem
[MPE1]; find a strategy [MPE2]; and show my work [MPE5].
To provide targeted practice with solving repeated addition
and repeated subtraction problems, place copies of the Math
Monsters Masters in a center.
