Rolling Along

The activities on this page are designed to get students to identify small groups of objects within a whole collection and to use these groups to count more efficiently. The students will be developing and using their ability to skip-count and/or partition to help them estimate accurately.  
Most people can see objects in groups of one, two, three, or four. The ability to see larger groups, such as five, six, or seven, is rare, but those people who can see groups of this size are able to count objects much more quickly than most people. Recent Australian research (Sue Willis, “Strengthening Numeracy: Reducing Risk”, ACER Research Conference 2000) has suggested that children from indigenous cultures may be able to see groups of larger sizes.

Activity One

If you don’t have marbles, the students could use beans or multilink cubes. Encourage the students to discuss and share their ideas about ways to count the marbles. Once they have suggested counting in twos, threes, or fours, you may need to reinforce skip-counting patterns using a hundreds board.
You could circle the marbles in groups of 2 or 3 or 4 on some enlarged photocopies of Hēmi’s marbles. You could also mark off the marbles into quarters to show how you could count a smaller section and multiply by 4.

Activity Two

The students may like to use a table to record their estimates, for example:

If the students continue to make unrealistic guesses, you could set up some trays containing 10, 50, or 100 marbles to serve as a guide.
As an extension, you could make connections to measurement. For example, you could ask: “If one cup contained 20 marbles, how many cups would be in a bottle that contained 120 marbles?”

Answers to Activity

Activity One
1. Between 60 and 70
2. Two faster ways are:

• skip-counting in 2s, 3s, 4s, and so on.

• dividing the tray into fractions, for example, quarters, counting the number of marbles in that quarter, and then multiplying it by 4.

Activity Two

Practical activity