Now that our seeds have begun to germinate (yeah!) it is time to discuss thinning. Thinning is the term we use to mean the removal of some plants to make room for others to grow. If plants are overcrowded they will compete for light and moisture and appear spindly and weak. To demonstrate, place two students back to back and ask if they would like to live the rest of their lives like that. Plants, like people, need ample room to develop.
To properly thin seedlings first select the largest and healthiest looking seedlings to keep, then grasp the seedlings next to it as close to the ground as possible and slowly and gently pull the plant out of the soil trying your best not to disturb the roots of the remaining plants. For small seedlings, use a scissor and snip the seedling off at ground level. This works very well with seedlings like carrots and lettuce. The back of the seed packet will tell you how far to space your seedlings apart, however with many vegetable plants like lettuce, arugula, spinach, and beets, thin your plants gradually and eat your thinnings as you go.
As a parent it is great to see this resource for school kids. You guys are doing a good job