Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 465 · 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.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) white paper (c) an adult with an iron (d) a small bowl
2. 2.⚖️ 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
3. 3.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
4. 4.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
5. 5.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
6. 6.True or false: putting the iron away is a job for an adult. (a) False (b) True
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
9. 9.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (d) putting the iron away
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
11. 11.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
12. 12.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) reading the message (d) putting the iron away
13. 13.⚖️ 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 keep it the same (c) we measure it
14. 14.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
15. 15.⚖️ 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
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
17. 17.True or false: putting the iron away is a job a child can do. (a) True (b) False
18. 18.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) reading the message (d) writing the message
19. 19.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
20. 20.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
21. 21.True or false: white paper is needed for the secret lemon message. (a) False (b) True
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a cotton bud (d) a battery cell
23. 23.True or false: letting the paper dry is a job for an adult. (a) False (b) True
24. 24.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) turmeric powder
26. 26.⚖️ 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 ironing time (c) the kind of juice
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a balloon (d) a battery cell
29. 29.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
30. 30.⚖️ 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 ironing time (c) how dark the writing is (d) the same paper
31. 31.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
33. 33.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
34. 34.⚖️ 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
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) white paper (c) an adult with an iron (d) a small bowl
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) a balloon
37. 37.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) reading the message (d) putting the iron away
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) yeast (d) a small bowl
40. 40.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) paper turns lemony (d) the iron is brown

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