Answer:
All though the two arguments are correct, I lean towards the 2nd argument. School gardens do not improve student's scores as they would if the student was well educated. The student will not learn from a garden. The surroundings will be better but can not help them. As it states in the second claim "America’s test scores continue to lag behind". Even if we have school gardens. But, the first argument is right in a way if the student is already well educated and knows the curriculum there surrounding may improve their learning by wanting to learn because they are more comfortable. These claims are strong because they do have facts and claims from others. They lean towards one side and are informative.
Hope this helps. : )