Firstly with this example, each object could have several values. There are no additional clues to help us identify what the green leaf, brown leaf and plant stalk are worth. I like that they have not used any numbers as clues on the left hand side of the equation either.
This example provides a little more information. I reckon the twigs may be worth 40 but then again, when you really stop and think, they could be any number between 1 and 45...
In the photo below, the group have given more examples. What has worked well here is that the reader can deduce the value of each object. The children have kept the values constant throughout their work. In other words, the small pebbles always have a value of 10. The twigs have a value of 6 and the leaves have a value of 8.
The next group have approached the task differently again. Each object has been assigned a value but has been multiplied by a number within the equation.
Often teachers worry about differentiating tasks in maths outside. I think this is a good example of how the children have demonstrated that they sort themselves out by the work they do. The opportunities for shared discussions around the results adds value to such tasks too.