A school held a physical experiment operation test, and * * * prepared three different experiments, requiring each student to participate in only one of them, and the students drew lots by themselves.

First draw a tree diagram according to the meaning of the question. From the figure, we can see that there are three situations and nine possible results when Liang Xiao and Dagang just do the same experiment, and then we can solve them according to the probability formula.

Solution: As shown in the figure:

Liang Xiao and Dagang happened to do the same experiment in three situations, and there were nine possible results.

So the probability = 3 ÷ 9 =.

So the answer is.

This topic examines the list method and the tree diagram method, and the knowledge points used are: probability = the ratio of the number of cases sought to the total number of cases.