Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 49 · 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: a small bowl is not needed for the secret lemon message. (a) True (b) False
2. 2.⚖️ 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 kind of juice (c) the same paper (d) how dark the writing is
3. 3.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
4. 4.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a cotton bud (d) turmeric powder
6. 6.⚖️ 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
7. 7.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
9. 9.True or false: putting the iron away is a job a child can do. (a) True (b) False
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
11. 11.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) plugging in the iron
12. 12.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
13. 13.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) plugging in the iron (d) letting the paper dry
14. 14.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
15. 15.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
16. 16.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
17. 17.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) putting the iron away
18. 18.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
20. 20.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
22. 22.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) letting the paper dry
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) lemon juice (d) white paper
24. 24.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) writing the message (d) letting the paper dry
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a cotton bud (d) a balloon
26. 26.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the ironing time (c) how dark the writing is (d) the kind of juice
28. 28.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
29. 29.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
30. 30.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it is sticky (d) it can burn skin
31. 31.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
32. 32.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) reading the message (d) writing the message
33. 33.⚖️ 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
34. 34.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
35. 35.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
36. 36.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
37. 37.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
38. 38.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) writing the message
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) white paper (d) lemon juice
40. 40.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed

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