# Subtraction Knock Down

## Subtraction Knock Down - Subtraction Math Game

Content Skill: Subtraction
Common Core State Standards: CCSS.Math.Content.2.OA.B.2 - Fluently subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.

## Description

If you like Angry Birds, you will love Subtraction Knock Down! In this game, you sling balls to try to knock all the boxes off the platforms. Each level is different and more difficult. Before you get to shoot a ball at the boxes, you will answer a subtraction fact. If you are logged into the student management system, the problems you answer will be based on the subtraction facts you are currently working on. Our probability engine chooses subtraction facts based on difficulty and your progress. This game is a challenging yet fun way to practice and learn the subtraction facts!

## Instructions

Step 1
Welcome to Subtraction Knock Down! Choose "Play" to begin the game. Select “How to Play” for the game directions.

Step 2
There are 18 levels to the game. As you pass each level by knocking down all of the boxes, another level will be unlocked.

Step 3
At the top left is the level you are on. You can also restart the level or end the level at the top left of the screen. The top right displays the time you have left. Sound Effects can be turned off by clicking the Sound Effects Icon. The music can be turned off by clicking the Music Icon.

Step 4
To fling the ball at the boxes, click and drag it back and move it around to aim it. Let go of the mouse to send it flying! The ball will follow the path you set.

Step 5
If you sling the balls with the right aim, they will knock down the boxes. The ball uses motion physics to bounce and hit the boxes in a realistic manner.

Step 6
After you sling the ball, you will need to answer a subtraction fact to get your next ball. Just click on the correct answer.

Step 7
If you don’t knock all of the boxes off the platform or you run out of time during the level, you'll lose! Just click on "Restart level."

Step 8
You'll win the level when you knock all of the boxes off the platforms. You have a choice of playing the level again to increase your score on the level  (Restart Level) or choose to go to the next level (Next Level).  You can also choose to replay any level you have already passed (Select Level) or return to the starting menu (Main Menu).