Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 876 · 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? Which of these is what we measure? (a) the same cotton bud (b) how dark the writing is (c) the same paper (d) the iron setting
2. 2.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) letting the paper dry (d) ironing the paper
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) an adult with an iron (d) white paper
4. 4.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
5. 5.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) a small bowl (d) lemon juice
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) lemon juice (d) white paper
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) blue (d) white
10. 10.True or false: writing the message is a job for an adult. (a) True (b) False
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
12. 12.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
13. 13.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) reading the message
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a mirror (c) lemon juice (d) a cotton bud
15. 15.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a balloon (c) a mirror (d) yeast
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
17. 17.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
18. 18.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
19. 19.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) reading the message (d) writing the message
20. 20.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
21. 21.⚖️ 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) True (b) False
22. 22.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
23. 23.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
24. 24.True or false: ironing the paper is a job for an adult. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
26. 26.⚖️ 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
27. 27.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) letting the paper dry (d) dipping the cotton bud
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a balloon (d) a cotton bud
29. 29.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) an adult with an iron (d) yeast
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
32. 32.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) ironing the paper (d) dipping the cotton bud
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a balloon (c) yeast (d) a magnet
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) an adult with an iron (d) a mirror
35. 35.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
36. 36.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
37. 37.True or false: cutting the lemon is a job a child can do. (a) False (b) True
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
39. 39.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
40. 40.⚖️ 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

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