STANDARDS

CCSS: 3.NBT.A.2, MP5, MP6, MP7

TEKS: 3.4A

Lesson: Feeding Frenzy

Objective: Students will use place value strategies to find the differences in bears’ weights before hibernation.

Vocabulary

Difference: the result of subtracting one number from another
Minuend: the number from which another number is subtracted
Subtrahend: the number that is to be subtracted

Lesson Plan

Spark Engagement.

Play the video “Getting to Know Grizzlies.” Then, before or after reading the article, spark a discussion based on the following questions:

How do some animals prepare for the winter?
Why is weight important to an animal’s ability to survive?
What other items could you compare a bear’s weight with? Explain.

Introduce the math concept and vocabulary.

Write the equation 18 + 7 = 25 on a piece of paper.
Addition and subtraction are inverse operations. What does this mean? (Answers will vary. Possible answer: Addition is the opposite, or reverse, of subtraction.)
How could you change your addition equation into a subtraction equation? (25 − 18 = 7) Allow a few volunteers to share their equations.
Have students identify and label the parts of their subtraction equation. The first number (25) is the subtrahend, the second number (18) is the minuend, and the result (7) is called the difference.
We can use place value strategies to help us subtract numbers.
Play the math video “Subtraction Strategies.”

Work through the "What to Do" box.

Why are 400 and 50 crossed out? (Possible answer: There were not enough tens to take 90 away from 50, so
1 hundred was borrowed from the 400 and it was regrouped into 10 tens.)
Where did 150 come from? Explain. (The hundred was taken from the hundreds column, regrouped into 10 tens and added to the 50. So, the 50 became 150 and the 90 can be subtracted from it.)
What inverse operation can you use to check your answer? Explain. (Possible answer: Addition. Add the difference, 161, to the subtrahend, 296, and the sum should be the minuend, 457.)

Reinforce with math practice.

Have students complete problems 1 through 4 on page 7 of the article.

Teacher's Tip

Use base ten blocks or coins to allow students to practice regrouping from one place value to add to another. This will help them connect the concrete to the abstract.

—Lauren McCrone, Education Editor, STEAM

Differentiate & Extend

Skills Sheets: Level Down: Subtraction With Number Lines (2.NBT.B.7) | On Level: DynaDash: Subtraction With Regrouping (3.NBT.A.2) | Level Up: Subtracting Across Zeros (3.NBT.A.2, 4.NBT.B.4)

SEL (Social-emotional learning activity/prompt): Bears spend the fall gaining a large amount of weight in preparation for the winter. Have students think about how they prepared for the start of this school year. Then have them make a list of actions they took to prepare and highlight any activities that were different this year than last year.

Dynamath@Home: Ask students to imagine that they have $250 saved. Then have them choose 3 items they would like to buy and research their prices. Have students determine which items they could buy and the amount they would have left over or the additional amount they would need to save to purchase the items.