Appeal to symmetry to simplify data taking. Work with circles of increasing radius to make the maps for different radial distances. This is an opportunity to work with polar coordinates explicitly, if you so choose. This is an opportunity to measure field strength by using the pendulum with a magnet on it. The magnitude of the magnetic force will be the product of the weight of the pendulum magnet and the tangent of the deflection angle of the pendulum from the vertical.
Students can measure the angle with a protractor and measure the mass of the magnet quite easily.
Students may need reminding that it is the shortest straight line distance from the position of the pendulum magnet to the current carrying wire that is to be measured and plotted. These two graphs can then be combined to yield the statement that the magnetic field of a long straight current carrying wire is proportional to the ratio of the current and distance from the current carrying wire. Next, have the students form a vertical loop in the wire and measure the direction of the magnetic field outside the loop. The goal is to motivate the right hand rule for field direction relative to the current in a wire. The set-up should be a circuit with voltmeter.