Group of ten tomato plants are germinated and maintained in a large tray with no drainage. after several weeks they all begin to wilt and die despite repeated watering and fertilization. the most likely cause of this die-off is

If the tomatoes were grown in a place or a kind of soil with no drainage then they are likely to die because one, too much water causes root rotting secondly there is poor circulation of air(oxygen) which is essential for plants survival. Remember air,water, nutrients are essential for growth of plants. Free circulation of air enables the roots to breath.this means that if there is poor drainage of water, there is poor circulation of air.
Why is oxygen important to the roots?
oxygen is necessary for plants to absorb nutrients.It is oxygen that transmits nutrients across the cell wall into the roots.

Oblate

Schools are being forced to embrace computers. unlike their "digital immigrant" teachers, these students are "digital natives", born into a world where technology is an integral part of everyday life. almost every student has access to a multitude of computers, laptops and tablet devices. it would be crazy to assume an assignment would  notbe written on computer in this day and age.many schools now have a 1-to-1 computer policy, and many districts and states in the united states have mandated computers or ipads across the state for every student,  including los angeles, the second largest school district in the country.but the thing is, when they tried it in la, it wasn't the success they hoped for. that's because the tablets weren't used as much as they expected. rather, it appeared there was a gap between the digital native's love of technology and their use of it in the classroom.this conflicted relationship with computers is also underscored by much of the literature on education. it is also highlighted in professional development and conferences such as  edutech.