Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 795 · 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.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
2. 2.⚖️ 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 measure it (c) we change it
3. 3.True or false: letting the paper dry is a job a child can do. (a) True (b) False
4. 4.True or false: cutting the lemon is a job for an adult. (a) True (b) False
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same cotton bud (c) the ironing time (d) the iron setting
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) lemon juice (d) a small bowl
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) a balloon (d) lemon juice
9. 9.True or false: putting the iron away is a job for an adult. (a) False (b) True
10. 10.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
11. 11.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a cotton bud (d) yeast
13. 13.True or false: writing the message is a job a child can do. (a) False (b) True
14. 14.🍋 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
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 iron setting (b) the same paper (c) the kind of juice (d) the ironing time
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) turmeric powder (d) an adult with an iron
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
18. 18.⚖️ 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
19. 19.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
20. 20.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
21. 21.⚖️ 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
22. 22.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
23. 23.True or false: ironing the paper is a job for an adult. (a) True (b) False
24. 24.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) reading the message
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
26. 26.🔮 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
27. 27.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
28. 28.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
29. 29.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) writing turns green (d) the paper floats
30. 30.⚖️ 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
31. 31.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
32. 32.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) plugging in the iron (d) putting the iron away
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) a small bowl (d) an adult with an iron
34. 34.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
35. 35.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
36. 36.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) putting the iron away (d) ironing the paper
37. 37.⚖️ 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 same cotton bud (c) the kind of juice
38. 38.True or false: letting the paper dry is a job for an adult. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
40. 40.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) ironing the paper (d) writing the message

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