Bar Model Solutions – by Students

After the post on Assessing Bar Model Solutions went up, Beth Curran sent a message: “We just did that problem!” She agreed to share some student work:

boys and girls 2

boys and girls 3

boys and girls 5

And when the students didn’t draw a model:

boys and girls 4

I see this as a comparison problem:

thinking blocks

5 units -> 125 students
1 unit -> 125 ÷ 5 = 25
7 units for boys -> 7 x 25 = 175 boys in all

(That’s the Thinking Blocks Model Drawing tool that allows you to insert your own word problems and solve – or you can use the pre-made questions!)


Fall 2015 dates for Model Drawing BER Seminar

Bar Modeling is my Force

Best. Seminar. Comment. Ever.

Here are the just-released Fall 2015 dates for my BER seminar “Boost Students’ Math Problem-Solving Skills Using Bar Models, Tape Diagrams and Strip Models (Grades 2-6)

Save the date!

A whole day of problem-solving with Bar Modeling, Tape Diagrams and Strip Models PLUS that handbook for your own home enjoyment! (- with the answers and fully worked solutions!)


“How to Use the Best Strategies From Singapore Mathematics to Strengthen Your Math Instruction” (BER) will have 10 dates in spring of 2016 – I’ll update when available.

Your city not on the list? Contact me and I can bring my Singapore Math® workshop(s) to your school or district – email Cassy (at)

Solving SAT problems using the model method

David Marain over at MathNotations has been periodically tweeting an SAT problem of the day via @dmarain. A recent series of tweets asked:

A 42 oz mix of nuts is 6 parts peanuts to 1 part cashews. How many ounces of cashews must be added to make a make the mixture 2 parts cashews to 1 part peanuts? Does Singapore (bar) model method work here?

Sure it can! Here’s one solution.

First model the beginning mixture at 6:1.

Singapore Math bar model

Next, we can figure out how many units need to be added to the cashews to make the cashews to peanuts ratio 2:1.

Singapore Math Model diagram - after

Since there are 11 additional units and the value of each unit is 6 oz, we can find the value of the added cashews.

Singapore Math units

66 ounces of cashews must be added to the peanuts to make the mixture 2:1.
Changing Ratios is taught in level 6A in the Primary Mathematics materials (U.S. Edition), typically used in 6th grade classrooms.