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### Speed! - Number Sense - Prime Numbers

Speed! is a fun game for learning multiplication, but playing Speed! also helps children develop a strong number sense. There are only a few days left in Speed! Celebration Sale so don't wait! Order your box on amazon today.

This is the fifth and last post in a series of posts - Speed! Number Sense - to explore different mathmatical concepts and how playing Speed! can facilitate understanding of these concepts.

The fifth concept is PRIME NUMBERS. With the exception of the

2 in Two Speed
3 in Three Speed
5 in Five Speed
7 in Seven Speed

Speed! does not contain any prime numbers. This is a hands-on activity to explain and visualize prime numbers upto 50 using Speed cards.

Open all eight decks of Speed cards and lay them out like this.

Start with Two Speed. Find a 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20. Lay them down leaving a space wide enough for another card inbetween each card. Lay down 15 more Two Speed cards with the back side up continuing down the line of cards. (Counting by two's, the highest number counted should be 50.)

Next lay down the Three Speed cards. Find a 3, 6, 9, 12, 15, 18, 21, 24, 27 and 30. Lay the 3 under the row of Two Speed cards between the 2 and the 4. Put the 6 directly under the 6 in Two Speed. Continue laying down the Three Speed cards leaving two spaces between each card. After the 30 card, lay down 6 more Three Speed cards with the backs facing up and leaving two spaces inbetween each card.

Continue in this manner with the remaining decks.

Once all the cards are layed out, look down the columns. There should be 11 columns which don't contain any cards. These are the prime number columns. There are 15 prime numbers under 50 when the 2, 3, 5 and 7 are also included.

Since this is a bit difficult to show with photographs, I also made an electronic version. The grey bars are placed over the columns which contain no cards and are therefore prime numbers.

The prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43 and 47. Notice that they all come before or after a card in Six Speed.