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General
Students learn to double and halve numbers to 20.
Common core standard(s)
2.OA.B.2
Relevance
It is important to be able to double and halve numbers, as they help you calculate easier and quicker.
Introduction
The interactive whiteboard shows four sports, basketball, volleyball, t-ball/softball/baseball, and football. Determine how many students in class play each of the given sports. You can do this by asking students who play basketball to stand up and then to count the number as a class (or have students count up and sit down). Repeat this with the other sports. At the end, you can discuss which sport is played the most, and which is played the least by your class.
Development
Explain to students that doubling means adding the same number again. Show this using the dots. You can then use the red and white beads to show that you can double by counting the same amount again. Students first double with visual support and then are asked to double without visual support. Next explain that halving, or splitting in half, means splitting the number into two equal numbers. Show this using the dots. Then use the red and white beads to show halving into two equal groups of beads. Students first halve with visual support and then are asked to halve without visual support.
To check that students are able to double and halve numbers to 20, you can ask the following questions:
- What do you do when you double a number?
-What do you do when you halve a number?
- What is the double of 8? And half of 8?
Guided practice
Students first practice doubling and halving with visual support. They are then asked to double and halve numbers without visual support.
Closing
Remind students what the learning goal of the lesson was. The interactive whiteboard shows two kids who each have 5 candies. Ask students to determine how many candies they have in total. Next show two kids, one of which as 16 candies, who wants to give half to the other kid. Ask students to determine how many candies each kid will have after halving 16.
Teaching tips
Students who have difficulties with this learning goal can make use of blocks or tokens to use while doubling and halving.
Instruction materials
Optional: blocks or tokens
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About Gynzy
Gynzy is an online teaching platform for interactive whiteboards and displays in schools.
With a focus on elementary education, Gynzy’s Whiteboard, digital tools, and activities make it easy for teachers to save time building lessons, increase student engagement, and make classroom management more efficient.