Beacon Lesson Plan Library

Triangle Town

Elisabeth Coogle


Students create a fact family town to develop the understanding of numbers related in fact families. Students learn each family has a big number and two baby numbers. They then make triangle shaped houses for their facts.


The student recalls (from memory) the addition facts and corresponding subtraction facts.

The student knows the related facts that represent the inverse relationships between addition and subtraction.


--Construction Paper Triangles
--Crayons or Markers
--Set of 18 math manipulatives for each student.
(Bears, dinosaurs, unifix cubes, geo tiles, or other counters will work.)
--Green and/or blue bulletin board paper
--Bulletin board border
--Triangle Town title for bulletin board
--Black paper for bulletin board roads
--1 copy of associated file for each student


1. Create a Triangle Town bulletin board by attaching green or blue paper as the background. The title of the bulletin board should also be displayed. You may want to cut black paper roads and add an attractive border.
2. Cut out large triangles for students using 9-x12- construction paper.
3. Collect other materials including a manipulative set of counting items.
4. Make copies of attached rubric - 1 per student.


1. Pass out 18 math manipulatives to each student. I use Koala Bear counters.

2. Explain to students that math facts live in families of 3. There is one big number and 2 baby numbers in every family. Furthermore, all fact families live in triangle houses.

3. Draw a triangle on a piece of construction paper. Put the number 8 at the top point.

4. Ask students to count out 8 of their manipulatives. Then ask students to divide their group of 8 into a group of 3 and a group of 5.

5. Now write a 3 and a 5 in the bottom two points of the triangle.

6. Show students how they can use this triangle fact house to help them add and subtract.

--Point as you state 3 plus 5 equals 8.

--Point as you state 5 plus 3 equals 8.

--Point as you state 8 minus 5 equals 3.

--Point as you state 8 minus 3 equals 5.

7. Now have students use their manipulatives. Repeat step 6 pointing to manipulatives instead of the triangle house.

8. Repeate the entire process with different numbers between 3 and 18 until students seem to understand the concept.

9. Tell students that they will now choose their own number between 3 and 18. Have students count out the correct number of manipulatives.

10. Pass out construction paper triangles. Instruct students to write their number at the top of their triangle.

11. Have students divide their manipulatives into two groups. Students count the manipulatives in each group and record the numbers in the bottom corners of their triangles. Refer students to the teacher model.

12. In the center of each triangle, students write the two addition and two subtraction sentences they can make with their fact family.

If students get done, they may decorate their fact family house or make another fact family house. All of the fact family houses will be displayed on a class bulletin board titled Triangle Town.

13. Allow students time to complete their houses.


Students' fact family houses will be graded using the attached rubric. Students will need to be able to state the two addition and subtraction facts that go with each house. Students should be able to answer all four questions, or the teacher will need to do remediation.


Most second grade math books have a section devoted to fact families or related facts. Students may complete worksheets with related facts.
A center may be created using the same materials. Students can continue to add to the fact town until all their facts are represented.

Attached Files

An assessment rubric is attached.     File Extension: pdf

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