Blue has given you some very good input.
Thanks for the photograph. The tank is different from the typical "corner aquarium" which will help if those are "live plants". If they are not and your daughter sees an aquarium with live plants then IMHO "welcome to the world of planted tanks".
Trash can LFS's thinking (I say this because he is so far off on cycling that he may have said other words which are just as far off).
The products which you are describing come in two forms:
The first has ammonia and nitrite in the solution.
This product is intended to shorten the cycling process by several days to a week as it eliminates the time period required to create these compounds in the tank water by several days to a week. The product is intended for use in a "fishless" cycle.
The second is purported to have live ammonia and nitrite digestion bacteria in the solution. IMHO these products are a scam as the bacteria needs a nutrient source in order to maintain life and how can this nutrient source exist in a sealed bottle (simple explanation: long one is very long).
The concept of cycling is simple (hopefully the link which I originally posted helped).
The cycle is intended to produce ammonia and nitrite digestion bacteria in the biological filtration media in your filter.
As you said daughter I feel that "time to see fishies" may be involved here and as such you might try the following (I am assuming that you used dechlorinator when you first filled your tank and the water temperature in your tank is 78F):
1) use your test strips to insure that the ammonia and nitrite concentrations in the water are 0 or very minimal values (A).
2a) purchase the platies and tetras and put them in the tank (B).
2b) I can also recommend the procurement of 7 Corydoras Sterbai. http://www.planetcatfish.com/catelog...species_id=316
These fish will
a) help with maintenance by scavenging on the bottom and
b) more importantly keeping your daughter entertained with their antics.
3) Feed the fish flakes (my flake food staple is TetraMin Tropical flakes) at the rate of 2 teaspoons per day (C).
4) Report back to us in a week the ammonia and nitrite concentrations in your tank.
i) I did not observe any oxygen bubbles in the photograph. As you are generating turbulence on the water's surface via the return flow from your filter you may not need additional oxygenation but then again too you may in the long term and your daughter might enjoy the air bubbles.
I can recommend air diffusion strips along the side of the tank or an air diffusion disk at the middle of the rear tank wall (I have both).
ii) Without floating vegetation your daughter will soon be observing "the big platties" eating all the "baby platties.
iii) Get your daughter prepared as the cycling process will take 21 to 28 days and until cycling is completed I cannot recommend the addition of other fish.
iv) Has your daughter seen any angel fish (as your tank appears to be 24" or 30" deep)? She might enjoy these fish as well as watching them grow.
(A) If you have not already purchased test strips IMHO you might consider purchasing a liquid test kit: I use the TetraTest kit.
(B) Many thoughts are set forth in the literature and posts on this forum as the best way to do this. The concepts extend from "a 20 day quarantine" to "rip open the bag and pour the fish and water in".
The two methods which I have employed include placing the bags in the tank water for an hour (temperature adjustment) and then
(1) cutting the top off the bag and gently pouring the fish and water in the tank or
(2) Gently pour the water and fish into a vessel, dip the fish out with a net and place them in the tank.
(C) Your daughter will enjoy this part! One teaspoon in the morning and one teaspoon 20 minutes before lights out. (this protocol can easily be varied to conform to your schedule.)