Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 206 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the same paper
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) lemon juice (d) white paper
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a small bowl (c) lemon juice (d) an adult with an iron
6. 6.⚖️ 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) False (b) True
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
8. 8.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) white paper (d) an adult with an iron
10. 10.⚖️ 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 keep it the same (c) we measure it
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
12. 12.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
13. 13.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) ironing the paper
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
15. 15.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
16. 16.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) writing the message
17. 17.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
18. 18.🛟 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
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a magnet (d) a small bowl
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) lemon juice (d) a battery cell
21. 21.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
22. 22.True or false: ironing the paper is a job for an adult. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
24. 24.True or false: cutting the lemon is a job a child can do. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
26. 26.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a balloon (d) lemon juice
28. 28.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
29. 29.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
30. 30.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
32. 32.True or false: letting the paper dry is a job for an adult. (a) False (b) True
33. 33.True or false: ironing the paper is a job a child can do. (a) True (b) False
34. 34.⚖️ 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
35. 35.⚖️ 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 kind of juice (c) the same paper
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a mirror (d) a cotton bud
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
38. 38.True or false: plugging in the iron is a job a child can do. (a) True (b) False
39. 39.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
40. 40.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed

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