standard_description: (+)Derive the equations of ellipses and hyperbolas given the foci, using the fact that the sum or difference of distances from the foci is constant.
problem_activity: Narrative
The purpose of this activity is for students to revist stage 2 of the Number Puzzles center which was first introduced in grade 1. Students work together to use digit cards to make addition and subtraction equations within 20 true. Each digit card may only be used one time on a page.
Required Materials
Materials to Copy
Number Puzzles Digit Cards
Number Puzzles Addition and Subtraction Stage 2 Gameboard
Required Preparation
Create one set of digit cards from the blackline master for each group of 2.
Launch
Groups of 2
Give each group a set of digit cards and game boards.
“We are going to play a game you may have played in first grade called Number Puzzles."
"In this game, you use digit cards to make each equation true. You can only use each digit card once on the game board.”
Activity
10 minutes: center work time
Activity Synthesis
Display Puzzle 1.
“Which equation would you start with? Why would you start there?”


aligns: no