1. Lesson Plan and Game
Nicole Pilarz

2. Explore Unknowns
(Expressions Unit 3 Lesson 1)
Class Information:
Grade-First
Number of Students-19
Time-Approximately 40 minutes
Room Set-up-There will be four tables with 4 to 5 students at each table. There will
also be a reading rug with a portable wipe-board easel in front of it.
Materials:
 19 individual wipe boards, markers and erasers
 19 Math workbooks
 10 cards with a number written on them
 10 sets of the game Addition Detective including (10 direction sheets, 10 game boards,
20 math mountain clue sheets, 20 pawns, 10 dice, 10 sets of cards).
Background Information:
This is the first lesson in unit 3 of expressions. Students have just finished taking the test on unit
2 where they learned to solve addition and subtraction equations and word problems. They also
spent some time comparing addition and subtraction equations, using one to solve the other. In
this lesson students will use counting on strategies to find the unknown partner in math
mountains. In future lessons students will move on to finding the unknown partner in addition
equations and word problems.
Big Ideas:
Math mountains can be used to find unknown partners and totals. Unknown partners can be
found by counting on using circle drawings, or your fingers.
Common Core Standards:
Operations & Algebraic Thinking 1.OA
Add and subtract within 20.
5. Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).
In this lesson students will count on to find the unknown partner in addition equations.
6. Add and subtract within 20, demonstrating fluency for addition and subtraction within 10.
Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14);
decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the

3. relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows
12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by
creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
In this lesson students will count on within 10 to find the unknown number in an addition
equation.
Work with addition and subtraction equations.
8. Determine the unknown whole number in an addition or subtraction equation relating
three whole numbers. For example, determine the unknown number that makes the
equation true in each of the equations 8 + ? = 11, 5 = _ – 3, 6 + 6 = _.
In this lesson students will determine the unknown number that completes various addition
equations that relate three whole numbers.
Student Objectives:
1. Students will be able tofind the unknown total in a math mountain.
2. Students will be able to use counting on strategies to find an unknown partner in a math
mountain.
3. Students will be able to play a game that requires them to find the unknown partner in a
math mountain without much teacher assistance.
Assessments:
Summative:
 Analyze student work in workbook
 Observe students playing game
Questions that may appear on a unit test:
Fill in the missing partner or total:
1). 2). 3.)
9 7
5 4 2 3
Formative:
List of questions to ask during the lesson:
1. Where do the partners go in a math mountain, what about the total?
2. Does it matter whether my unknown partner is on the left or right?
3. If I switch the partners in a math mountain does it change anything, why or why not?
4. When counting on using circle drawings, how do I know what my answer is?

4. 5. Can there be more than one type of math mountain for the same total?
Anticipatory Set:
1. Call students to the rug one table at a time.
2. Tell students that we are going to be magicians and I want to show you a special trick.
Call 2 students to stand in front of the class and give them each a card with a number on
it. Tell them that they can look at the card but can’t show the rest of the class.
3. Ask one of the students standing to add the 2 cards together, tell the class the total. Write
the number on the board.
4. Now tell the other student to show the class their card. Write it on the board.
5. Now that we know the total and one of the partners can we guess the number the other
student is holding in their hand?
6. Use think pair share to discuss answers. Then ask one student to reveal their guess, are
they right?
7. Discuss strategies for getting their answer. Do this 2 more times.
LessonProcedure:
1. Call students back to their seats one table at a time and ask them to take out their wipe
boards, markers and erasers.
2. Draw a math mountain on the smart-board. Does anybody remember what it is called?
3. Talk about on a math mountain where the total goes and where the partners go. Label
them.
4. Use the analogy of rocks rolling down either side of the mountain.
5. What happens if we switch the partners, does this change our math mountain? Discuss
why or why not.
6. Now draw a math mountain that is missing the total on the board and ask students to
draw the same one on their wipe boards. Ask them to find the total. Do this a few more
times discussing answers.
7. Now have students draw a math mountain with a missing partner. What is one way we
can find the answer?
8. Tell students that counting on and drawing circles will help us. Keep the partner that
they know in their mind and then count on until they get to the total. Draw a circle for
each number they say. Do an example together.
9. Make sure students know that their unknown partner is the number of circles they drew.
Not the last number they said. That number should be the total.
10. Do a few more examples together switching up the side the missing partner is on. Do our
methods change if the missing partner is on the other side?
11. Now ask students to open their workbooks to page 65. Try finding the missing partners
in the first row by drawing circles. Go over the answers.
12. Now tell students that drawing circles can take a lot of time. Is there an easier way to
find the missing number? Lead them to say counting on using fingers.

5. 13. Instead of drawing a circle, lift up a finger for each number you count on. The number of
fingers you are holding up is your answer.
14. Try counting on with fingers for the next 2 rows. Go over answers together.
15. Now explain that we are going to play a math game to help us withmath mountains. Call
students to the rug.
16. Explain the game “Addition Detective”. Then have them split into partners around the
room to play the game. They will play the game for about 10 minutes and I will walk
around the room observing game play.
17. Explain that they are going to be able to take this game home and teach their parents or
somebody in their house how to play and bring it back the next day and tell us who won!
Closure:
1. Have students go back to their seats calling them one table at a time.
2. Tell students that on their wipe boards I want you to create as many math mountains as
you can for the number 7. (This is just like our partners of 7 that we did earlier in the
year. Think about our math stairs.) Give one example.
3. When all students are finished ask them all to stand up. I am going to call on one student
at time to give me one of their math mountains. If you have the same one on your board
erase it.
4. When all of your math mountains are gone, sit down. By the end of the closure we
should have all possible math mountains for 7 listed on the board.
Independent Practice:Students will take home the game “Addition Detective” so that they may
play it with their parents or someone else at home and practice the skills they learned during this
lesson.
Written Materials:All written materials are attached.

6. Dear Parents/Guardians;
My name is Nicole Pilarz and I am a senior student at Buffalo State College in the Elementary
Education Program. Over the past couple of months I have had the opportunity to work with
your children in Mrs. Smith’s classroom twice a week, observing and occasionally teaching math
and science lessons. Teaching has always been a passion of mine and this opportunity has only
increased my excitement in one day becoming a teacher myself. I have truly enjoyed working
with your children and am happy to admit that I am not only helping them learn, but learning
from them as well.
Recently in math we have been working on finding the unknown number in an equation. For
example; 5+___ =9. One method we have been using to help find the missing numbers are
called math mountains. They look like this:
In order to help your child understand this concept I have created a fun math game called
“Addition Detective” that you and your child can have fun playing together, while learning at the
same time. We have already taken the time to play this game in class so your child should
understand the rules. However; all the materials you will need to play the game; including the
directions, are attached to this letter. Once you’ve read the directions it is important to note that
it would be most helpful for your child if they found the missing number before moving their
player. This way they are doing the math and not simply counting on.
I encourage you to take this opportunity to help your child learn, and most importantly have fun
playing together. Please sign this letter and feel free to leave me comments about the game.
Any type of feedback would be helpful.
Sincerely,
Nicole Pilarz
Parent/Guardian Signature:____________________________________________
Comments:

7. Directions
It’s time to put on your detective hats! These equations are missing numbers, can you figure
out what they are?
Before you start:
 Place the pile of cards face down
 Place your players on start
On your turn:
Step 1: Pick a card. (Example: My card says “Make 7”.)
Step 2: Roll the dice. (Example: I rolled a 4.)
Step 3: Use your detective skills to find the missing number.
(Example: I have to make 7 and I already have 4 so that means my missing number is 3
because 4+3=7.)
*Every game includes a sheet of math mountains that may help you find the missing number,
but it is not mandatory to fill it in. This is how it works:
Step 4: Move your player that number of spaces. (Example: Now I can move forward 3 spaces.)
Now it is the next players turn. Play will continue in the same way until somebody reaches the
finish line. The first person to the finish line is the winner!
*Another example; if your card says make 6, and you roll a 6, then your missing number is 0
because
6+0=6. In this case you do not move.
*If you land on a space that says -2, +2, -3, or +3, move forward or backward that number of
spaces.
*If you run out of cards, shuffle the deck and continue playing.
*If you run out of space on your clue sheet, create your own math mountains on the back.
Fill in your missing number
here.
This is the number on your card. It is
already filled in.
Fill in the number you rolled
on your dice here.

8. Math Mountain Clue Sheet
Make 6:
Make 7:
Make 8:
Make 9:
Make 10

9. ADDITION DETECTIVE
-
START
FINISH!
-2
+3
+2
-3