Saturday, March 17, 2012

Multiplication: Week One

Day 1: Zeros and Ones

Show the students your driver's license and ask them the following questions:

What is this? [A driver's license]
What does it mean? [You're allowed to drive and you know what you're doing.]
How did I get it? [By learning how to drive, learning all the rules, and then passing a test.]

You can't get your driver's license until you're sixteen, but there's another kind of license that you can get earlier. Most kids don't get it until they're in third grade, but you have learned so much math and worked so hard that we're going to see if you can get yours in FIRST GRADE!
We're going to work on multiplication for the next two weeks, and learn all the rules to follow. If you pass a test at the end, I will give you your very own multiplier's license. (Take a picture of each student at some point during the unit to put on their multiplier's license.)

Introduce the "×" symbol. What does this mean? Why do some people call multiplication
"times"? (Because you're adding that number together a certain number of times.) We are going to learn two whole sets of times tables today, and I promise you can all learn them.
Write some zero multiplication problems on the board. Teach the students the proper
words for reading these number sentences. (e.g. "x times y equals z.")
Teach the students that no matter what they multiply by zero, the answer is always zero. You can make this fun/funny by using word variables. (e.g. "What's zero times banana?" "Zero!")

Teach multiplication by one in the same manner. No matter what I multiply by one, it stays the same. Tell them that these two are both very easy, but they're also easy to mix up! Have the students sit in a circle for a short game. (What about zero times one? Does it follow both rules?)

Tell them that this is the lightning round, and they have to answer their questions as quickly as possible. Walk around the outside of the circle and ask students 0's and 1's
multiplication questions in turn. If they get it right, they get a small treat (like a chocolate chip or
Skittle.) The faster they go, the more chance they'll have for treats. (But try to emphasize accuracy too!)

Day 2: Twos and Review

Review doubles addition facts using the "lightning round" game from Day 1. Did you know that if you can add doubles, you can do 2's multiplication? Draw examples on the whiteboard to illustrate that multiplying by two is doubling (which we already know how to do!) Say multiplication problems aloud and have students use unifix cubes to model them. (Can you show me two groups of five? What number sentences can I write on the board that show this? (5 + 5
= 10, and 2 × 5 = 10.)

When the students seem comfortable with this concept, briefly review 0's and 1's (and model with unifix cubes if there's time), then tell them that they're doing so well that they're ready for their first test.

Day 3: Threes and Fours

Give each student a handful of unifix cubes (~24) and ask them to line them up in groups of three. If they have one or two left over that don't fit into a group of three, they can put them back in the box. If we want to quickly see how many cubes you have, a good way to do that is multiplication or skip counting! Since every group has three in it, we'll find the answer if we skip-count by threes. (You may want to model this with one student's blocks or on the white board.) (If students are unsure about counting by threes, write the numbers on the whiteboard for reference.) Ask the students to skip-count their blocks by threes, then go around the circle and tell how many you had. (All numbers should be multiples of three.)

That's all we have to do to multiply by threes! Teach students that skip counting is another way of doing multiplication. If we want to know what three times six is, we can skip count by threes until we get to the sixth number (3, 6, 9, 12, 15, 18!)

Repeat the exercise for fours- line up unifix cubes in groups of four (discard any remainders), practice skip-counting your groups, and tell how many you had. (Answers should be multiples of
four this time.)

Give students the skip-counting worksheet. Show them (either on the worksheet or on the board) that when they have the skip counting lines done, they can just count over to do their
multiplication like we did earlier!

Day 4: Fives and Tens (Multiplication with Coins and Clocks)

Review 10 times tables. ("Just add a zero!") Review skip-counting by fives and how to find the answer to 5's multiplication problems using this method.

Give each student a handful of dimes and nickels and an index card. Tell them that you're going to pull items out of the bag and tell them the price. (Or have students take turns pulling an item out of the bag and announcing the price.) Students will then need to put the correct number of dimes and nickels on their card to represent the price. Have students check their neighbors to make sure that everyone is figuring things out. On the smaller-priced items, ask students to show the price using just dimes, then the same one using just nickels.

If you have extra time, review telling time (to five minute increments). Tell students that if they learn their five times tables, telling time will be even easier! Then instead of counting all the way around the clock, they can do the multiplication problem in their head to find the number of minutes. Practice this with the small clocks.

Encourage students to practice over the weekend. We're going to have a practice test on Monday so we can get our multiplier's licenses!

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