Froggy Subtraction

Explicit Instruction/Teacher modeling

• Tell students that today they will practice jumping on a number line to solve subtraction problems. Display a number line that includes at least 0 - 20.
• Write 18 - 4 on the board, have students read, "Eighteen minus four."
• Model finding 18 on the number line, and have students repeat, "Eighteen" exaggerating the n so that 18 is not confused with 80.
• Ask students whether the numbers will get bigger or smaller when you subtract. Ask students to point in the direct that you will move on the number line to subtract.
• Think aloud, "Yes, when I add the numbers get bigger and I move forward on the number line." Tell students to point in front of themselves and repeat, "forward."
• Say, "With subtraction I will start will the whole, and subtract one part. I will need to move backward on the number line to find the missing part." Have students point behind themselves and repeat, "backward."
• Refer back to the problem and say, "I need to subtract four." Model jumping back four times on the number line counting each jump, "One, two, three four."
• Ask students which number you landed on (fourteen!). Solve the equation and have students read the equation with you as you point below, "Eighteen minus four equals fourteen."

Guided Practice

• Distribute the Froggy Subtraction number line and game piece to each student. Tell students that they will follow along on their number lines to solve subtraction problems, and then play a game with a partner.
• Write 15 - 3 on the board and chorally read, "Fifteen minus three."
• Direct students to line the frog up with 15, as you model on the number line.
• Ask students whether you will move forward or backward on the number line to subtract three. Think aloud, "As I subtract, the numbers get smaller."
• Model jumping back three numbers as students follow along with their number lines. Remind students to count the "jumps".
• Finish the equation 15 - 3 = 12, and have students read with your chorally.
• Continue with a few more examples using the number line to subtract.

Group work time

• Distribute a die to each partnership, and tell students that they will now play Froggy Subtraction with their partner.
• Project the instructionsm and explain the steps to play the game. Each player will start at 20. Player A will roll the die, and count that many jumps backwards. Player A will say a number sentence, "____ minus ____ equals ____."
• Player B will roll the die, move the frog that many jumps, and say a number sentence.
• The player must land exactly on 0 to win. For example, a roll of four cannot win if the player is on 3.
• The first player to reach the fly wins! (Optional- tell students to add to return to the lily pad to win.)