Mathematics Lesson Plans

Elementary Lesson Plans

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#262. Teaching fractions & ratios with M&Ms

Begin by reviewing fractions (if already taught), including the appropriate terminology (numerator, denominator, etc.). I taught this lesson shortly after Hallowe'en, so I began by asking students what they usually do with their Hallowe'en candy when they get home. I fielded responses, then told them that I used to sort my candy into piles (classifying it by types or colours or whatever). Then I told the students that M&Ms were always my favourites. I asked them if they knew how many colours of M&Ms there are (6). What are they? (blue, brown, red, orange, yellow, green) I set up a chart on the blackboard with those colours listed vertically in a column. Then I told the class that I had a total of 15 brown, 10 blue, 5 red, 6 orange, 12 yellow, and 12 green. I asked them to find the total number of M&Ms I had (60). Then I asked the class to give me a fraction to represent the total of each colour. You get 15/60 for brown, etc. Then as a class I asked students to reduce the fractions using division to their lowest form. So you have 1/4 for brown, etc. These fractions (both the initial and reduced form) are to be recorded beside the colour on the blackboard chart. At this point, if fractions are a new thing for students, you may want to spend some more time on what's been done so far. If fractions have been learned and you've intended this lesson to segue into ratios, then keep reading...Introduce the class to the concept of ratios. Tell them that a ratio is a comparison using division of 2 numbers. Ratios can be written in 3 ways (1:4, 1 to 4, and 1/4). Have students brainstorm to see if they can come up with the three ways (or maybe tell them that the fraction is one of the ways, can they come up with the other 2?). With all three ways written on the board, have students read aloud the way one "reads" a ratio (E.g. one to four). Have students fill in the last column of the blackboard chart with the ratio representations of the fractions. The whole class portion of the lesson is over. Now for the fun part...

Have students work alone or in pairs at their desks. Distribute the baggies with 20 M&Ms in each one. Have students copy a chart like the blackboard chart into their notebooks. They will be filling the charts in with their own data from their M&Ms bags. They will begin by tallying each colour, then give fractions and reduced forms for each colour, then they will write ratios for each colour. Before students begin, explain the ground rules to them: the M&Ms can be eaten at the beginning of their work but then they will be given less interesting and less fun textbook work to do. If they wait just a bit, they will discover that eating the M&Ms is actually built into their work assignments! After writing all their ratios, tell the students to start eating the M&Ms, but they must stop eating them 2 times before they are devoured and redo all their ratios. For example, they might choose to eat 10 of 20 M&Ms- at this point they would rewrite the new ratios for each colour (don't forget this involves a new denominator!). This lesson worked really well with my grade 6 class (during my practicum)- all students were interested and motivated throughout the entire lesson, of course many suffered from a slight sugar high afterwards...

Good luck!