
Problem type  # of tasks  PSTs example  Number choices 

Join Change Unknown  5  “Joshua collects rocks. He likes to keep them in bags of ten. Last week he had a total of ____ bags. After finding some more this week, he now has ____ bags. How many rocks did Joshua find this week?”  Number Choices: 5, 6) (5, 8) (8, 12) (9, 15) 
Join Result Unknown  8  I would create JointResultUnknown (JRU) or SeparateResultUnknown (SRU) problems for the students. A JRU example would be “Sunny has ____ fish, and then she buys ____ more. How many fish does she have now?” Number choices would include  Number Choices: {(10, 50) (20, 30) (10, 41) (15, 25)}. 
Compare change unknown  1  Emilio had 64 soccer cards. Sunny had 28 soccer cards. How many more soccer cards does Emilio have than sunny?  
Separate result unknown  4  Emilio has __soccer balls. __ Soccer balls roll away. How many Soccer balls are left?  Number Choices: (15, 5) (26, 16) (57, 27) (81, 51) 
Group size unknown  2  Jack has 65 pencils. He wants his 5 classmates to each have an equal amount of pencils. How many would each classmate get?”  No number Choices 
Number of groups unknown  3  Sunny has 94 chocolate chips. She needs 10 chocolate chips to make a cookie. How many cookies can Sunny make?  No number Choices 
Both product unknown & Joint Result Unknown  4  Sunny has 8 rolls of candy. Each package has 11 candies in it. She also has 12 extra candies. How many candies does she have in all?  No number Choices 
Product unknown and compare result unknown  1  Mary had __ bags of cookies with __ cookies in each bag and Amy had __ bags of cookies with __ cookies in each bag. Which one had more cookies?  No number Choices 
Relational thinking problems  1  40 + 60 =  +   No number Choices 
True/false sentences  1  10 + 2 = 6.  No number Choices 
10 + 5 = 5 + 10 
10 + 10+10 + 9 = 20 + 19 
