Grade
K
How Many Are Hidden? Shifting Shapes
What do you notice? How many shapes do you see?
![A large triangle made with smaller shapes. The top row is 1 small triangle. The middle row is 1 trapezoid. The bottom row has 2 small triangles, a rhombus, and then 1 more small triangle.](/sites/default/files/styles/large/public/inline-images/yOYqCpQZp7M6QitEFRB38ix7gI3F7m1aXFGJvgCGehqD6twnNR.png?itok=ZK_dAwM-)
Now some shapes are hiding behind the big square.
How many are hidden? Use math words, numbers, or pictures to explain how you know.
![The top parts of the big triangle are hidden. The bottom row is still 2 small triangles, a rhombus, and 1 more small triangle.](/sites/default/files/styles/large/public/inline-images/daMrywTdL0ED1ugd5lioL4kvAFhCN9hdnktM9Xnqa3G3j7Jqqg.png?itok=ikG2ZGRV)
Challenge
Now we can see which shapes were hiding! What equations match the picture? How do you know?
![The bottom of the large triangle has four shapes. The top part of the triangle has 2 shapes.](/sites/default/files/styles/large/public/inline-images/mb3ln7rZlOJL4BE1Izy6Nu91gG5ZU5lsTjix6Z04SeKOUlhrub.png?itok=pseR3mlw)
6 − 2 = 4
6 = 3 + 3
4 + 2 = 6
5 + 1 = 6
Follow-up
How could you remove different shapes from the large triangle to make a smaller triangle?
![A large triangle made with smaller shapes. The top row is 1 small triangle. The middle row is 1 trapezoid. The bottom row has 2 small triangles, a rhombus, and then 1 more small triangle.](/sites/default/files/styles/large/public/inline-images/qdNcKZ6BKWM9D7j3253T9gspv4g7gegixqnlFadZIQgOUAH4To.png?itok=lokLn5Be)
Printable Version
Google doc for printing and copying
Seesaw Version
Activity for the Seesaw platform
Reference for Educators
Sample problems and solutions