A Visit From Biomes

This is off topic but last Thursday, 5th graders enjoyed a visit from Biomes Marine Biology Center.  This kicks off our next science unit where students will learn about and observe a variety of marine life. Take a look at some of the samples that Shelby (our Biomes presenter) brought to the red pod.

Students were given a free pass to Biomes, which is open to the public.  Visit their website for directions, their hours of operation, and the cost of admission.  They are moving to a new location soon so check on that before going. 

Hope everyone is enjoying the weekend.

Mental Multiplication of Multi-Digit Numbers Ending in Zero

Here's more video of the mental math strategies we're working on this month.  Here, you'll see my helpers putting a box around the zeros so they can focus on the basic fact. I refer to this as putting the zeros in your pocket.  After solving the basic fact, they take the zeros out of their pocket and put them in their answer. 

I apologize that the numbers in the video are a bit difficult to see.  The problems that are being solved are 200 x 40, 500 x 40, 60 x 80, 300 x 800, and 70 x 30.

As I said in the previous post, some students will jot down the numbers in order to give an answer.  With enough practice, some students will be able to look at the problem on a flashcard and give the answer without writing anything down.  Students may use whatever process works for them, in class as well as on quizzs and tests. 

Mental math strategies are tested periodically, but are not timed.

Special thanks to my helpers for demonstrating their math skills on camera.  You know who you are.  :)   

Computational skills in Unit 4 include mentally multiplying 2-digit numbers by 1- digit numbers.  Students begin by taking the 2-digit number and breaking it down into its tens and its ones. 

Watch my helper demonstrate this process.

You may wonder why this is called mental math when you just watched my helper writing numbers down.  The goal is that with enough practice, less and less writing of the numbers will be necessary.  As you saw, some students will eventually be able to arrive at the correct answer without writing anything down.  Some students will only need to jot some of the numbers as they think it through, and other students will continue to write out the entire thought process.  All of these variations on the process are valid and may be used during class work as well as on quizzes and tests. 

Special thanks to my student helper for participating in this video.  (You know who you are.)  Thanks also to everyone at home for taking the time to read this blog.  Stay tuned.  There's more video to come.

Student-Written Word Problems

1.  Aspen had 80 dog toys.  She chewed some of them.  How many toys are left?

    Solution:  (80 - n)                                          written by   T. O.

2.  Andy and some friends bought 20 pieces of bubble gum each.  Each piece of gum costs 5 cents.  How much money was spent in all?
   
    Solution:  (20 * .05) b                                    written by B. B.

3.  Mrs. Schart had 30 math papers.  Her students threw away half of them.  She copied some more.  How many papers does
     she have now?

    Solution:  (30-15) + m                                    written by R. B.

4.  There is 1 Zack.  Ten more Zacks come in and some Zacks leave.  How many Zacks are left?

    Solution:  (1 + 10) - z                                      written by Z. A.

5.  Bob and his brothers went to buy a bag of chips each.  Each bag costs $3.00.  How much money did they spend?

    Solution:  (1 + w)3                                          written by T. N.

6.  Four people went to the store.  Each bought a bag of apples.  There are p apples in each bag.  How many apples in all?

    Solution:  4p                                                    written by K. W.

My thanks to all the students who shared their work in front of the class today.  Well done!

Unit 4

Happy New Year everyone!  We've settled back into our routine here at school and have begun Unit 4.  It breaks down like this:

Review Skills

• Coordinate graphing (like playing the game Battleship)
• Divisibility - This was introduced in Unit 1 and students have a list of divisibility rules in their math folder.  They may refer to it as needed.  This skill will be helpful and important when we study fractions.

Computational Skills

• Long division with remainders
• Mental math strategies using multiplication and division

New Material

• Division word problems where students must interpret the remainders 
• Algebraic word problems
• The commutative property of addition (a + b = b + a) and multiplication (a x b = b x a)

Here is a sample of a problem where students must interpret the remainder:

There are 123 guests attending a wedding.  They will be seated 10 to a table.  How many tables are needed?
Solution: 123/10 = 12 r 3    There will be 12 full tables and 3 people without a seat.  13 tables will be needed.


A basic algebraic problem looks something like this:

Kevin has 10 marbles in his collection.  He wins some more marbles during a game at recess.  When he goes home that afternoon, he gives 5 of his marbles to his younger brother.  Write an expression to show how many marbles Kevin has now.
Solution:  (10 + m) -5

The trickiest thing for students to understand is that the algebraic expression is their answer.  The word problem doesn't provide enough information to lead them to a final numerical answer.  As we progress through this unit, sometimes students will be given a value for the variable such as If m=7, how many marbles does Kevin have now?

We will practice this extensively in class and eventually, students will be ready to tackle more complex word problems.  They will also think this through in reverse by taking an algebraic expression and writing a word problem that fits it.

As always, if students find this material difficult and so are unable to complete homework, we trust that they will do their best to find something there (no matter how small) that they can attempt.  Each day, we will go over the previous night's homework aloud and answer questions.  Students may then complete the work as we are discussing it, or ask to see something they struggled with done on the board.  Our cooperative groups earn bonus points when someone is brave enough to raise their hand and ask a question or ask for help understanding something in class.