Refresh students on the concept of adding fractions with example of two pizzas cut into equal slices (8 slices each)
Ask students how many slices they want of pepperoni pizza and what the fraction would be to describe it. (Example: 2 slices= 2/8)
Do the same for cheese pizza. (Example: 3 slices= 3/8)
As a class, add the total slices together in terms of a whole pizza. (Example: 2/8 + 3/8= 5/8 of a pizza)
2 Direct Instruction
Ask the students what would happen if the cheese pizza were cut into 6 equal slices? Would 3 slices from that pizza be the same amount as three slices from the pizza cut into 1/8's?
It doesn't make sense to add different sized slices to find a total number of slices eaten. We have to recut the pizza into equal sized slices in order to to find a total number of slices eaten that makes sense.
The "Adding Fractions Animation" at mathisfun.com allows us to do just that while walking us through the steps of reslicing the pizzas and rewriting our fractions.
3 Guided Practice
Ask students for any clarification questions.
Solve problem on board with student-guidance, asking students not only why they chose each step but why they avoided common missteps (such as adding denominators)
4/9 + 7/18
4 Independent Practice
Write three problems on board for students to write down and complete independently
Students fold notebook paper longways so they can work the equation on left side and write down steps/logic on right side. Have students draw their own pizzas for at least one problem.
2/3 + 2/5
1/4 + 5/6
3/8 + 3/4
Check for errors as students work
Assign worksheet with practice problems for homework. Require written explanation of thought process for two problems as well as one problem where students draw the fractions in each stage as pizzas and one problem where students create their own visual to demonstrate the fractions.