Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 723 · 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.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
4. 4.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) lemon juice (d) a mirror
6. 6.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
7. 7.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
8. 8.True or false: reading the message is a job a child can do. (a) True (b) False
9. 9.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
11. 11.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
13. 13.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
14. 14.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) ironing the paper (d) putting the iron away
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the ironing time (c) the same paper (d) the same cotton bud
16. 16.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) lemon juice (d) white paper
19. 19.True or false: ironing the paper is a job for an adult. (a) True (b) False
20. 20.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
21. 21.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) reading the message
22. 22.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the iron setting (c) how dark the writing is
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) it turned into air (d) the paper ate it
25. 25.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
26. 26.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) yeast (d) a cotton bud
28. 28.True or false: cutting the lemon is a job for an adult. (a) False (b) True
29. 29.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
30. 30.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) white paper (c) a magnet (d) a balloon
32. 32.True or false: letting the paper dry is a job for an adult. (a) True (b) False
33. 33.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) writing the message
34. 34.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) dipping the cotton bud (d) writing the message
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) white paper (d) a small bowl
36. 36.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) an adult with an iron (d) lemon juice
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the iron setting (c) how dark the writing is (d) the kind of juice
39. 39.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a cotton bud (c) white paper (d) lemon juice

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