Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 466 · 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 “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
2. 2.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) heat adds colour (d) the iron is brown
3. 3.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
4. 4.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
5. 5.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
6. 6.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) cutting the lemon (c) ironing the paper (d) putting the iron away
7. 7.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
8. 8.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) plugging in the iron (d) putting the iron away
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
10. 10.True or false: writing the message is a job for an adult. (a) False (b) True
11. 11.⚖️ 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) False (b) True
12. 12.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) any child (d) the youngest child
13. 13.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is magnetic (d) it is cold
14. 14.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
16. 16.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
17. 17.True or false: white paper is needed for the secret lemon message. (a) True (b) False
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a small bowl (d) an adult with an iron
19. 19.True or false: letting the paper dry is a job a child can do. (a) True (b) False
20. 20.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
21. 21.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
22. 22.⚖️ 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
23. 23.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
24. 24.⚖️ 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
25. 25.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a magnet (c) a small bowl (d) lemon juice
27. 27.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) plugging in the iron (d) reading the message
28. 28.🍋 Which of these steps is a job a child can do? (a) reading the message (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
29. 29.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) writing the message (d) dipping the cotton bud
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a small bowl (c) an adult with an iron (d) a cotton bud
31. 31.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) writing the message
32. 32.⚖️ 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
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
34. 34.⚖️ 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
35. 35.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
37. 37.⚖️ 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
38. 38.🧺 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 small bowl (d) a mirror
39. 39.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) turmeric powder (d) an adult with an iron
40. 40.⚖️ 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

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