Guessing Jar Math

Mrs. St. Onge's guessing jar is no ordinary guessing jar. 

Mrs. St. Onge and her guessing jar are a mighty math marvel!

Throughout the day, children visit the guessing jar and estimate the amount of objects in the jar. They sign their name and write a guess on a piece of paper, adding it to a basket. A number line is handy and is a clue to help with guessing and printing numbers.

At the end of the day, she begins to get the children ready for math thinking with a familiar song, sung to the tune of 'Do You Know The Muffin Man?'

Do you know the Guessing Jar, 

The Guessing Jar,

The Guessing Jar?

Do you know the Guessing Jar?

How many in the Guessing Jar?

The familiarity of the song is a clue to start the thinking of estimation. 

And then she begins!

This day, there were 3-dimensional shapes in the guessing jar.

As the shapes were taken out of the jar, Mrs. St. Onge talked about them.

"How many faces on this shape?"

"This shape has a rectangle base and four triangle faces.  

It's called a triangular prism."

"Who knows what we call this shape? Who wants to guess?"

"What does this shape remind you of?"

Many of our children excitedly answered what they already knew about the shapes.

She sorts each shape as they finish talking about them.

A mighty mouthful of math!

 

Now the shapes were sorted into five groups.

The amount of shapes in each group were counted.

Then, the amount in each group was added to a final total.

"1, 2, 3. Three rectangular prisms added to two cubes equals five shapes. Now let's add on. Let's see, where were we? 5 shapes and 1, 2, 3 triangular prisms.  

How many shapes are there now?"

Mrs. St. Onge models strategies like counting each shape one by one and 

using fingers to add up totals.

A mighty mind full of math!

Finally, it's time to see who has the closest guess.

It has to be a guess! No counting the shapes in the jar and putting the answer down.

As each name is drawn, the children help to decide if the guess is too high (in a high-pitched voice) or too low (in a low-pitched voice). Talk of the direction of numbers and how a two digit number is printed (eg. 81 or 18) is mentioned. The children are thanked for visiting the guessing jar and encouraged for their effort.

Winners of the guessing jar get a trip to the prize box!

Marvelous, mighty math from Mrs. St. Onge!

More tips for a guessing jar.

Vary the sizes of the jars and the sizes of the objects.

Big jar, small objects.

Small jar, big objects.

Use object groupings (eg. all dominoes, all paper clips, all dinosaurs of varying sizes, etc...)

Use language like predict, more, less, up, volume,

 space, amount, estimate, total, similar, size