Mental Math For the Win

Mental math includes the ability to add and subtract some numbers without actually needing to count. 

When it comes to adding and subtracting 100, students apply their knowledge of place values. In other words, they know that the digits in the tens and ones places don’t change, but the digit in the hundreds place increases by 1. 

In this activity, students will show they can use algebraic thinking to find 100 more or 100 less than a given number. 

Make It Easy to Add & Subtract 100

Use this resource in your math center, guided small group, or with your whole class (see below) to practice identifying the missing number that is either 100 more or less than numbers up to 1,200 

Students will review each task card and write the missing numbers from the patterns in their corresponding space on the recording sheet. 

More Ways to Help Students Add & Subtract 100

Use this resource as independent practice for fast finishers and full-class learning opportunities like scoot activities, lesson reviews, formative assessments, and more.

🛴 Scoot Activity

Hang all 20 cards around the room in order and provide students with a recording sheet. Working either alone or in pairs, assign a task card to each to start, and have them rotate around the cards (on your signal), writing their answers on the recording sheet.

☀️ Warm-Up/Exit Activity

Either before or after your math lesson, ask students to select a task card from the deck. Have them write their card number (1-20) and their name in the top corner of a sticky note, and finish the sequence by writing the missing number. Use our simple sticky note printing template to make this assessment a snap!   

👯‍♀️ Mirror Game

This activity is a spin on the classic “Newlywed Game” and works best with small groups because you’ll need enough dry erase boards and markers for each student. Divide the students into 2 groups, and have them sit in 2 lines facing each other. Project a task card and give students 10 seconds to complete the sequence on their board. On your cue, the students turn their boards around so their partner can see their answers. If both students in a pair have the correct answer, they get 2 points. If one has the right answer, the team gets 1 point. 

Easily Prepare This Resource for Your Students

Print on cardstock for added durability and longevity. Place all pieces in a folder or large envelope for easy access. 

Keep the task cards out of pockets or under desks: cut out the cards and punch a hole in the corner of each to place them on a binder ring. 

To turn this teaching resource into a sustainable activity, print a few recording sheets on cardstock and slip them into dry-erase sleeves. Students can record their answers with a dry-erase marker, then erase and reuse.

Before You Download

Use the dropdown icon on the Download button to choose between the PDF or Google Slides version of this resource. A recording sheet and answer key are also included with this download.

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This resource was created by Allie Kleijnjans, a teacher in Pennsylvania and Teach Starter Collaborator. 

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