Rich Learning Tasks

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Planting Trees Number
Questions to facilitate the learning
• How could you have predicted it would take less than 20 minutes?
• Who is faster—Mia or Kyla? How do you know?
• Why did you have to change the description of at least one or both of the rates to help you?
Scaffolding the learning
• How long does it take Kyla to plant a tree? Is that information useful?
• How many trees can Mia plant in an hour? Is that information useful?
What’s the point of this task?
In order to solve this problem, students are likely to work with equivalent (unit) rates. Knowing that Kyla can
plant 300 trees in an hour also tells you she can plant 5 trees in a minute or that in 12 seconds she can
plant one tree. Knowing that Mia can plant one tree in about 13 seconds means she can plant 4 trees in
52 seconds, so about 4 1
2 trees in a minute or about 270 trees in an hour. Then students need to think
about how knowing how many trees the two, together, can plant in a minute or the number of seconds it
takes each to plant a tree, helps them figure out how long it would take to plant 100 trees.
A number of the questions below focus on using the information given to estimate. Estimation should
always be encouraged in ratio and rate problems.
Extending the learning
Students might choose different speeds for Kyla and Mia that would require them to need exactly 12
minutes to plant 100 trees.