Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 486 · 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: plugging in the iron is a job a child can do. (a) True (b) False
2. 2.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, in the dark (d) yes, if cooled
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) white paper (d) yeast
5. 5.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
6. 6.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a magnet (d) a small bowl
8. 8.🔮 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
9. 9.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
10. 10.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
11. 11.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the same paper (d) the kind of juice
13. 13.⚖️ 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
14. 14.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
15. 15.True or false: cutting the lemon is a job for an adult. (a) False (b) True
16. 16.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
17. 17.⚖️ 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 iron setting
18. 18.⚖️ 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
19. 19.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) writing the message (d) plugging in the iron
20. 20.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
21. 21.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) writing the message
22. 22.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) an adult with an iron (c) white paper (d) lemon juice
24. 24.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
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 measure it (c) we keep it the same
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
27. 27.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) reading the message (d) writing the message
28. 28.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) a magnet (d) an adult with an iron
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the iron setting (d) how dark the writing is
32. 32.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) brown (d) green
33. 33.⚖️ 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
34. 34.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
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) lemon juice
36. 36.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
37. 37.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
38. 38.🔮 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
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
40. 40.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) plugging in the iron (d) ironing the paper

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