For each problem, decide whether it is a JRU type, or SRU.
1. Shauna had 4 balloons. 3 of her balloons popped. How many balloons did she have left?
SRU: The action of balloons popping decreases the number of balloons.
2. Jane made 5 origami animals. Later she made 1 more origami animal. How many origami animals did she make in all
JRU: The action of making another origami animal yeilds an increase over time in the number of origami animals
3. Diana had 12 grapes. She ate 3 of her grapes. How many grapes did she have left?
SRU: The action of eating the graphs decreases the numebr of grapes.
4. Blake had 4 Beyblades. For his birthday, he got 1 more Beyblade. How many Beyblades does he have now?
JRU: The action of getting another Beyblade increases the number of Beyblades.
5. Marie had 6 stuffed animals. When she cleaned her room, she found 1 more stuffed animal. How many stuffed animals does she have now?
JRU: The action of finding another stuffed animal is an increase over time.
6. Laura had 11 marbles. She gave 2 of her marbles to Alex. How many marbles did Laura have left?
SRU: The action of giving away marbles decreases the number of Laura's marbles.
Decide for each statement whether it is true or false.
7. The first step in modeling both SRU and JRU problems is to count out the starting amount of counters.
True: In an SRU problem you count out the starting number of counters, and then take some away; in a JRU problem you count out the starting number of counters and then add some in.
8. Some Join and Separate problems have an amount that changes over time, but some don't.
Both answers could be correct, depending on the justification. Join and Separate problems have to have an associated action that can change an amount over time (so it is false that some don't have that sort of action), but if the amount that the start amount is changed by is 0 (so if you take away or add on 0), then the start amount doesn't actually change (which is the one situation under which it would be true that some Join and Separate problems don't have a change over time)
9. JRU problems are easier for children to direct model than SRU problems.
False. At the direct modeling stage, these problems are equally easy/difficult. It is only when the child starts using more abstract solution strategies that SRU problems become more difficult.