Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 963 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
2. 2.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
3. 3.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
7. 7.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
8. 8.True or false: writing the message is a job a child can do. (a) False (b) True
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) yeast (c) an adult with an iron (d) lemon juice
10. 10.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
11. 11.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) the paper floats (d) it gets darker
12. 12.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
14. 14.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a magnet (d) an adult with an iron
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the ironing time (d) the same paper
18. 18.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
19. 19.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
20. 20.🍋 Which of these steps is a job a child can do? (a) reading the message (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) a balloon
22. 22.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
23. 23.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) putting the iron away (c) plugging in the iron (d) ironing the paper
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a battery cell (d) an adult with an iron
25. 25.True or false: white paper is needed for the secret lemon message. (a) False (b) True
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) lemon juice (d) a mirror
28. 28.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
30. 30.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) an adult with an iron (d) a mirror
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the iron setting (c) the kind of juice
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
33. 33.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) reading the message (d) putting the iron away
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
35. 35.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
36. 36.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
37. 37.True or false: plugging in the iron is a job a child can do. (a) True (b) False
38. 38.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) dipping the cotton bud
39. 39.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
40. 40.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) the paper ate it (d) it turned into air

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