Wednesday, April 29, 2015

April 29 on Earthquake

Rushi was rescued after being trapped for 82 hours in the recent earthquake in Nepal.

How many days is 82 hours?

Notes for Parents | Encourage mental strategies. Instead of doing long division for 82 / 24, get students to think of 82 as 48 and 34 and 34 as 24 and 10. From there it is easy to see that 82 hours is 3 days and 10 hours. 

When practicing computations, make sure they acquire number sense. What I described is one way to develop number sense.

Monday, April 27, 2015

April 28 on Airbus

Singapore Airlines A380 at LHR.

Since 2000, the A380 has won just 317 orders, less than a third of the 1,200 Airbus projected in its first 20 years.

Why is 317 less than a third of 1200?

Notes for Parents
Can your 11-year olds do mental arithmetic such as a third of 1,200?

Challenge your child to explain if Airbus is expected to meet its sales projection for the first 20 years.

Saturday, April 25, 2015

April 24 on Food

I paid £8.45 for three food items. Is that possible?

Notes for Parents
Is that possible opens up a child's thinking.

It is fine for children to learn computation but make sure that's not all they learn.

Can your child say that one if the food item must be burgers? That's having number sense.

If a child can compute flawlessly and no able to make deductions like that then he or she had procedural understanding but not number sense. This often happens when parents and teachers overemphasize drills and computations. The mind becomes desensitized. 

Saturday, April 18, 2015

April 16 on Naked Juice

This is my favourite drink because it's yummy and its bottles have cool information I can use to challenge more able students.

What is the fewest number of bottles that can be obtained by using whole number of each of peach, orange, mango and apples?

In preparing two bottles, a peach and an orange are needed but only a third of a mango is used and half an apple got left over. So the number of fruits used are not all whole numbers. 

Notes to Parents 
If your child is advanced, refrain from accelerating him or her. In other words, it is less fruitful to move on to learn to multiply two-digit numbers if the child gets his times table easily than to have enrichment opportunities.

The above task is an enrichment task for advanced learners.

April 15 on Tomatoes

Tomatoes cost $1.98 per pound. 
How much does 4 lbs cost? | Grade 3 onwards 
How much does 2.5 lbs cost? | Grade 5 onwards

Notes for Parents
Encourage your child to do more mental strategies. Reciting times tables is not doing mental math. 

Hopefully your Grade 3 child will be able to say that it's almost $8 for 4 lbs. Even better if he can say it's 8 cents less than $8. If your child is advanced she should be using clever mental strategies all the time.

Grade 5 children should be able to handle 2.5 lbs. They should be able to say half a pound cost half a dollar plus half of 98 cents. Even better if he can give the final amount as 99 cents for half a pound and 2 cents less than $4 or $3.98 for the 2 lbs. $3.98 + 99 cents = $4 + 97 cents.

Encourage mental strategies in computations of friendly numbers. Use a calculator otherwise. There is no room for tedious computation by hand.

Sunday, April 12, 2015

April 9 on Cups and Saucers

This tray to place cups and saucers holds seven rows of cups and a row of saucers. Its width is about 5 cups wide or 3 saucers wide. With the cups stacks two cups high and the saucers  ten saucers high, what is the greatest number of cups and saucers it can hold? Comment on your answer. 

April 11 on Gym Lockers

The lockers are numbered consecutively and are in a rectangular arrangement. 

075 and 081 are next to each other. 

How many lockers are there from top to bottom?

April 10 on Buddha

At 39.5 cm, this piece of art is exquisite. But it is not in any museum. It was impounded by a Samut Prakan police station and is now sitting in some storage place in another province. I wonder what's the story.

There are five rows of smaller Buddhas forming the base. 11 statues on the lowest base and one fewer in each successive steps. 

How many smaller Buddhas make up the base? 

What if the height of the entire work is doubled by keeping the height of the largest Buddha and increasing the height of the base - how many small Buddha statues are needed on the lowest step? 

April 8 on Pathlight Mall

Pathlight Mall sells cool stuff. These notebooks (SGDx.90) and coasters (SGDxx.90) are based on the art work of a student, Jun Yi, who draws cute animals in groups, interacting.

I bought 2 sets of coasters and 5 notebooks as gifts. I paid a total of SGD87.30

Is it possible to figure out the unit price for each item? 

Monday, April 6, 2015

April 7 on Wings

Mr Tan wants to get two drumlets for each of the 37 children in his Primary 3 class as a treat for achieving 15 'clever days' in a month. What is the least amount of money he needs to spend on the drumlets?

In Singapore, prices are inclusive of 7% GST.