Grade 3 Bar Models: Part-Whole Bar Models

Worked examples

Real problems from the practice worksheets, solved one step at a time.

1. Example 1

   Emma has 217 red stickers and 362 blue stickers. How many stickers does Emma have in all?

   1. Draw one bar for all of Emma's stickers, split into two parts: 217 red and 362 blue.
   2. We know both parts and want the whole, so add the parts. 217 + 362: add the hundreds and tens, then the ones. 217 + 360 = 577, then 577 + 2 = 579.
   3. Emma has 579 stickers in all.

   Answer: 579

2. Example 2

   Emma has 510 balloons. 108 are red and the rest are blue. How many are blue?

   1. Draw one bar for all 510 of Emma's balloons. One part is the 108 red ones; the other part is the blue ones we need to find.
   2. Whole − known part = missing part. 510 − 108: take away the hundreds, then the ones. 510 − 100 = 410, then 410 − 8 = 402.
   3. 402 balloons are blue.

   Answer: 402

3. Example 3

   Jack has 806 marbles in all. Some are red and 590 are blue. How many marbles are red?

   1. Draw one bar for all 806 marbles. The 590 blue marbles are one part; the red marbles are the missing part.
   2. Whole − known part = missing part. 806 − 590 = 216.
   3. 216 marbles are red.

   Answer: 216