3rd Grade - Be Able To Solve Similar Problems

Be Able to Solve Similar Problems
Note the method of deriving the solution and demonstrate a conceptual understanding of the derivation by solving similar problems.
Mathematical Reasoning: problem solving The ability to think one’s way through a word problem, even if it requires more than one step, perform the correct mathematical operations and be able to explain to others how the problem was solved. Also, the ability to solve similar problems, thus proving that the student understands the mathematical principles involved rather than just memorizing the solution to a single, unique problem.

Sample Problems


What does multi-step mean? (more than one step)


If your mom makes a batch of a dozen cookies and she sells half at the school bake sale. She gives 5 to the children helping at the bake sale and eats one herself. How many are left? (none)


If a dolphin can jump 6 meters into the air and you can jump 2 feet, who can jump higher? (the dolphin)


The baby used 6 cloth diapers a day and the family only did the wash every three days. How many diapers are there to wash? (24 diapers) If wash day is missed and a week goes by, how many diapers will there be? (42 diapers)


There are 16 M&Ms in each cookie and we divided the cookie into four parts. About how many M&Ms are in ¼ of the cookie? (4 M&Ms) How many M&Ms are in 2 dozen cookies? (384)

Learning Tips


Present your child with a word problem that requires a single mathematical operation (addition, subtraction, multiplication, division, for example.) After reading it over, ask your child to draw a picture that indicates what to do. For addition, two groups of items might be circled together. For multiplication, several groups of the same-size sets might be circled together. For subtraction, the original number of items might be represented with circles and the required number crossed out, leaving the remainder. For division, items might be re-grouped into same-size sets until the original group is completely re-sorted. Then ask your child how he/she “knew” what to do. Discuss other examples of problems that can be solved in the same way.


For multiple-step problems, try to find a real-life situation in which to experience the solution. A common word problem presented to children of this age requires them to add two numbers and then subtract the answer from a larger number. If your child has the opportunity to go to the store, select two small items for purchase and then ask your child to state how much change should result from the money that is provided for payment (not exact change. There is a good chance he/she can figure it out, using these manipulatives (the toys, the money) and can then write a rule to use when similar problems appear on paper.


If your child is having considerable difficulty with word problems, make sure that your child can actually read them. Many children are considered “poor” at word problems when the reality is that the child simply can’t read the problem, or finds the reading so difficult that by the time he/she has finished puzzling out the words, there is no time left for solving it—or the child has already forgotten what was asked.


Explain to your child that word problems are often written as little stories and that in order to make them “interesting” there are often details in the story that have nothing to do with the problem to be solved. Don’t encourage your child to believe that he/she was “tricked” but rather, to realize that everything we read isn’t of equal importance and in some occasions what we read is meant to be ignored in the solving of the word problem. Ask your child to make up some problems in which this is the case to see if he/she really has grasped this concept.


Sometimes the values needed to solve problems are implied and require that the child possess common cultural knowledge. For example, “a dozen” means that the value needed for the problem is 12. If some measurements in the problem are expressed in inches (or cups) and others in yards (or quarts) your child needs to know these equivalents.

Extra Help Problems


There were 12 girls and 4 troop leaders in the Girl’s group. The leader asked them all to work in four groups. How many groups were needed? (4)


Horton had 6 pretend tattoos. He bought 18 more and divided them at school amongst his 12 friends. How many did each friend get? (2)


Betsy had three dollars worth of quarters. She lost 3 quarters. How much money did she have left? ($2.25)


Nick’s dad went to buy a six-pack of soda for the weekend. It was on sale so he bought four six-packs. The three kids drank one each day of the weekend and Nick’s dad drank two each day. How many are left for next weekend? (10 are gone, so that leaves 14)


Hildi is saving up to buy a new pair of pants for $60. She works each Tuesday and Thursday after school babysitting and earns $5 per hour. She works two hours each of those days. How many weeks will it take her to save up for the pants? (3 weeks)


Carrie weighs 95 pounds. Her sister weighs 4 pounds less. She said: ‘Together, we weigh the same as our Dad!’ How much does their Dad weigh?


For an easier version of the measurement problems, children can use a cheat sheet with conversions written on it.

Mary is baking cakes. She needs 8 ounces of sugar for every cake. She has a 5-pound bag of sugar. She makes four cakes. How many pounds of sugar does she have left? (3 pounds)


3 oranges weigh 32 ounces altogether. One weighs 12 ounces. Another weighs 10 ounces. What is the weight of the third apple? (10 ounces)


Nickie had a 10-pound bag of rice. She cooked rice for four people. She cooked 8 ounces of rice per person. How many ounces of rice were left in the bag? (136 ounces)


Avery had a gallon bottle of juice. He poured out four 2 pints. How many quarts were left in the bottle? (3 quarts)


A bottle of plant food had 1 quart of liquid nutrition inside it. Sandra took 1 cup of plant food two times a week and poured it over her garden. After 2 weeks, how much did she have left? (none)


Some children had a 2-quart water bottles. They poured 4 pints of water into the bottles. Then they poured 1 pint down their throats. How much more is needed to fill the water bottle in cups?

(2 cups)


A carton of watermelon juice holds 8 ounces. They are sold in packs of three. Ben buys two packs. How many ounces of juice is that? (48 ounces)


Lisa started watching TV at 4 pm. She watched a show on Channel 4 for 30 minutes, then a game show on Channel 7 for 60 minutes. Then she switched the TV off. At what time did she switch it off? (5:30pm)


Diane and her mom went shopping. They left home at 9:00 am. It took them half an hour to get there. Then they spent 2 hours in the shops. It took them 10 minutes to get home. At what time did they get home? (11:40am)


The train from Los Angeles to Long Beach left at 10am. It should take 30 minutes. It was 15 minutes late. What time did it arrive in Long Beach? (10:45am)


On May 18th, Candy said: It is one week until my birthday. Danny said that his birthday was 2 days before Candy’s.

What is the date of Danny’s birthday? (May 23rd)


Our teacher had 25 yards of rope. She cut off three pieces that were all 5 feet long to make jump ropes.

What was the length of the rope left over? (20 yards)


Some children were growing a daisy. At the end of the first week, it was 2 inches tall. In the second week it grew another 4 inches. In the third week it doubled. How tall was the daisy? (12 inches)


A boat was going to the islands and traveled 150 miles. In the first hour they traveled 50 miles. In the second hour they traveled 65 miles. How much further did they have to go? (35 miles)


Jan is making flower planters. She wants to make 3 planters that are 1 yard long. She had a piece of wood that is 5 yards long. What length of wood will be left over? (2 yards)


Cole collected rare dollar bills. He purchased two eagle dollars for $212 and then sold them for $95 each. Did he make or lose money and how much? (lost $24)


Dane jumped on the trampoline for 2 hours and did 15 successful flips each hour. How many flips did he do? (30 flips)


It was New Year’s Day and Jonah couldn’t wait for his uncle’s party in exactly one week. What date is the party? (January 7)


If the pizza has 36 pieces of pepperoni spread evenly and is cut into 6 pieces, about how many pepperoni slices are on each piece? (6 slices)


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