I love this! Practicing combinations to 10 can be repetitive and boring, OR it can be like this. The practice students get with combinations to ten with this simple trick is purposeful and engaging. Students will want to practice this and “perform” it for everyone! See below for ideas to provide students with an audience.

The video below, shows a performance of this trick. The goal is to provide a reason for students to practice their combinations to ten. In the process of introducing this problem, students smile – a lot. The wonder created by introducing this to students makes the smile and question: “How do you do that?” almost automatic.

How this trick works:

After presenting this to students, ask them what they noticed as you introduced the “trick.” They may say that they saw 5 and 5 or 7 and 3. They may say they think that tens are involved. Let students know that this whole “trick” is based on making tens. Teach students how to do this and then pair students and have them work together to practice. Speed is not important. The goal is to practice and work to become better. The brief video below shows how to perform this trick

After teaching this to students pair them up to practice and tell them they will have time to practice for several days to make sure they can do this for some “guests” coming in (see below for ideas). The reason for pairing students is to provide support, not just because you “need” two people to do this. As students work, if someone gets stuck because they forget what to do next, or they are not sure about a combination to ten, that’s where the partner steps in to help:

• How can I help you?
• What has you stuck?
• Let’s work through this together.

All students will benefit from working and practicing this way.

After students have practiced and can perform this well, provide them with an audience (i.e., administrators, coaches, other teachers, other classes, parent math nights, etc.)

Why this trick works:

Watch the brief video below to see a brief explanation showing the mathematics behind why this works.

Supports:

This “trick” is very scalable. For students needing support, you can start with combinations to 5 (as seen in the how and why videos above), then work your way up to combinations to 10. Just be sure to remove the appropriate cards. For combinations to 5, just use the aces through fours. Combinations to 6, just use the aces through fives, etc. Additionally, instead of having three cards selected, two cards can be selected, then you can have students work up to three.

For older students, this can be introduced as a problem to be solved. How can you find out the values of the cards selected? In this case, it might be useful to show the video of the performance above instead of performing it yourself (because you want to figure it out as well).